Updated

An armed group battling Macedonian police over the weekend left 22 people dead and aimed to destabilize the country with terror attacks, the country's president declared Sunday in a nationwide television address.

President George Ivanov spoke after an emergency meeting of Macedonia's National Security Council in the capital, Skopje. He had cut short his visit to Russia on Saturday, the day the armed clashes began in the northern town of Kumanovo.

"Police have prevented coordinated terrorist attacks at different locations in the country that would cause serious destabilization, chaos and fear," Ivanov said. "The members of the group are extremists and criminals with remarkable military training and skills. That's why we have paid such a high price with the loss of lives."

The attacks left at least 22 people dead, including eight police and 14 attackers, Interior Ministry spokesman Ivo Kotevski said.

The Macedonian government declared two days of mourning Sunday for those killed in the clashes. Flags were flying at half-staff and sports events and political gatherings were canceled.

Prime Minister Nikola Gruevski told reporters the group of over 40 armed men had planned to attack state institutions, sport events and shopping malls and said they had combat experience both in the region and in the Middle East. He said the group was not supported by members of Macedonia's ethnic Albanian minority.

The fighting comes as Macedonia is grappling with its deepest political crisis since its independence from the former Yugoslavia in 1991. The government and the opposition have accused each other of planning to destabilize the country to take or preserve power and some analysts fear leaders on both sides are ready to provoke ethnic clashes.

Kotevski named five leaders of the armed group, all citizens of Kosovo, as founders of paramilitary cells. He said the group entered Macedonia at the beginning of May to launch attacks on state institutions and hid out in Kumanovo's western neighborhood, where police found a huge arsenal of weapons.

Kumanovo is an ethnically mixed town 25 miles northeast of Skopje, near the border with Kosovo and Serbia. The region was the center of hostilities between ethnic Albanian rebels and government forces during the ethnic conflict in 2001. That insurgency ended with a Western-brokered peace deal that granted more rights to ethnic Albanians, who make up about a quarter of the country's 2 million people.

Gruevski praised the police, who also saw 37 members wounded. Three dead policemen were later buried in the town of Tetovo, west of Skopje.

"Macedonian police have performed the most complicated operation and the police forces, with officers from all ethnic groups, have performed a professional, heroic and patriotic operation," Gruevski said at a press conference.

Police have filed terrorism-related charges against more than 30 members of the group who surrendered. They were brought before an investigative judge late Sunday to be questioned.

Kotevski said some of the slain attackers wore uniforms with the insignia of the disbanded ethnic Albanian Kosovo Liberation Army but had no identification documents on them. The ethnic Albanian rebel group fought Serb government forces in 1998-99 for the independence of neighboring Kosovo.

About two weeks ago, authorities said about 40 wearing UCK uniforms attacked a police watchtower in Gosince on Macedonia's northern border with Kosovo and briefly captured four Macedonian police officers.

EU Enlargement Commissioner Johannes Hahn expressed "deep concern" at the situation around Kumanovo.

"Any further escalation must be avoided ... in the interest of the overall stability," Hahn said.

Observers from the Organization for Security and Cooperation in Europe (OSCE) were in Kumanovo to tour the site of the armed clashes. The European Union, NATO, OSCE missions in Macedonia and U.S Embassy in Skopje issued a joint statement, pointing that "the armed group in Kumanovo is an isolated phenomenon."

"We strongly believe that it must not be allowed to harm relations within society. We also hope that this will be the moment for the country's leaders to pull together and engage in dialogue on all issues facing the country, including the protracted political crisis and necessary reforms," the statement said.