The Syrian regime widened artillery attacks on opposition strongholds Tuesday in another sign that the U.N.-brokered cease-fire is quickly unraveling despite the presence of foreign observers, activists said.

U.N. chief Ban Ki-moon said he is asking the European Union to provide helicopters and planes for the observers because of the ongoing violence and the long distances monitors would have to travel.

The truce is part of an international plan to launch talks between President Bashar Assad's regime and an opposition trying to topple him. But the regime has only partially complied with the terms, and the latest escalation in attacks lowered already minimal expectations that international envoy Kofi Annan's plan will stick.

The overall level of violence is down since the cease-fire formally took effect Thursday, but the regime has gradually stepped up attacks. The number of people killed every day has also risen steadily since a brief lull that coincided with the start of the truce.

More than 9,000 people have been killed since the uprising to oust Assad began 13 months ago, according to the U.N.

The central city of Homs has been under continuous assault for about a month, with only a brief lull on the first day of the cease-fire. In a six-minute amateur video posted Tuesday, shells are heard falling on Homs at intervals of one every few seconds. Gray or black smoke rises from several locations at once, at times filling the entire screen.

Annan, joint emissary for the U.N. and the Arab League, was in Qatar briefing the Arab League on Syria. His plan has the backing of Assad's allies, including Russia, and even with setbacks it is seen as the only way forward because Western military intervention is unlikely at this point.

Still, French Foreign Minister Alain Juppe said international sanctions are starting to work and have wiped out half of Syria's foreign currency reserves. Juppe was speaking to representatives of 57 countries gathered in Paris to coordinate economic measures against Assad. Syrian foreign reserves were believed to be around $17 billion at the start of the uprising in March 2011.

In Moscow, leaders of two Syrian opposition groups said Tuesday, a day after meeting Russia's deputy foreign minister, that they have sensed a shift in Russia's stance and hope Moscow will crank up pressure on Assad. Russia twice shielded Assad from U.N. Security Council condemnation, but has become more critical of the regime.

"Russia has all the necessary levers to apply pressure on Assad's government and help Annan's mission," said Haytham Manna, leader in exile of the National Coordination Body for Democratic Change in Syria.

Manna's group is seen has having more clout in Syria than other opposition groups, which are made up of mostly exiles. Still, the National Coordination Body has failed to gain significant international traction as the Syrian crisis grows.

U.N. chief Ban portrayed the violence as only "sporadic." But he suggested an observer mission of 250 members, as envisioned originally, may not be big enough "considering the current situation and considering the vastness of the country."

The Security Council is to approve the terms of the mission later this week, after talks between Ban and Syrian authorities. Speaking in Luxembourg, Ban said he has asked the EU to provide planes and helicopters for the observers.

A six-member advance team of U.N. monitors arrived in Damascus over the weekend. U.N. officials said the team is still devising a plan on where to go and whom to meet.

A previous Arab League observer mission was hampered by regime restrictions on movement, and Ban has demanded his monitors be given free access. The head of the observer team, Col. Ahmed Himmiche, suggested it would take time to get to the hardest hit areas. Work in Syria is "difficult," he said in Damascus.

"There should be coordination and planning. ... We must walk step by step as it's not an easy process."

The group is to be reinforced by an additional 25 monitors who are expected to arrive in the next few days, he said.

In violence Tuesday, army tanks shelled the southern town of Busra al-Harir, killing at least two people, according to the Britain-based Syrian Observatory for Human Rights. The town, about 70 kilometers (45 miles) south of the capital of Damascus, is a stronghold of the rebel Free Syrian Army.

Adel al-Omari, an activist in the area, said troops have been shelling Busra al-Harir and the nearby rural region of Lajat since midday Monday. He said the shelling was intensifying and that many residents are fleeing to nearby villages or to Jordan.

An amateur video posted online Tuesday showed the inside of a Busra al-Harir home whose windows had been blown out and walls peppered with shrapnel from shelling.

Regime forces also fired mortars and shells at the neighborhoods of Khaldiyeh and Bayada in an apparent push to take control of the rebel-held districts in Homs, a center of the rebellion against Assad, according to the Observatory. Homs has been under continuous regime attack, with only a short break on the first day of the cease-fire, activists said.

Amateur video showed frequent explosions sending up gray smoke clouding the horizon over a residential area of Homs, apparently from shelling. Another video purported to show the dead body of an activist in a rubble-strewn street in the city's Bab al-Dreib neighborhood. An off-camera narrator said no one had been able to retrieve the body for days due to snipers.

The Observatory also reported the use of mortar fire by regime forces in two areas of the northwestern Idlib province. On Monday, 10 people were killed in a daylong gunbattle between rebel fighters and the Syrian army in the city of Idlib.

In all, at least 26 people were killed across Syria on Monday, the Observatory said. Another activist group, the Local Coordination Committees, said at least 55 people were killed Monday, including 26 in Idlib.

Across the border in Lebanon, Hassan Nasrallah, an Assad ally and chief of the Lebanese militia Hezbollah, said he reached out to Syrian opposition leaders, proposing they talk to the regime, but was rebuffed.

"You have an opposition that is not prepared for dialogue ... all it wants is to bring down the regime," Nasrallah said in an interview by video link with WikiLeaks whistleblower Julian Assange, aired on Russia's Kremlin-backed broadcaster RT

Nasrallah has rarely been seen in public since his Shiite Muslim group battled Israel in a monthlong war in 2006, fearing Israeli assassination. Since then, he has communicated with his followers and gives news conferences mostly via satellite link.


Associated Press writers Bassem Mroue in Beirut, Vladimir Isachenkov in Moscow and Mark D. Carlson in Luxembourg contributed reporting.