SERHANIYEH, Lebanon-- Syria is planting landmines along parts of the country's border with Lebanon as refugees stream out of the country to escape the crackdown on anti-government protests, officials and witnesses said Tuesday.

The exodus to neighboring Lebanon and Turkey has proven a deep embarrassment for increasingly besieged President Bashar Assad, who warned over the weekend that the Middle East will burn if foreign powers try to intervene in his country's conflict.

A Syrian official familiar with government strategy claimed the mines are meant to prevent arms smuggling into Syria. The official spoke to The Associated Press on condition that his name not be published because of the sensitivity of the matter. Witnesses on the Lebanese side of the border also told the AP they have seen Syrian soldiers planting the mines in recent days in Syrian territory in the restive province of Homs.

"Syria has undertaken many measures to control the borders, including planting mines," said the Syrian official.

More than 5,000 Syrians have fled to Lebanon since the crisis began in March.

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The landmines are the latest sign of just how deeply shaken the Assad regime has become since the uprising began nearly eight months ago. Assad, a 46-year-old eye doctor who trained in Britain, still has a firm grip on power, although the cost has been mighty: The U.N. says some 3,000 people have been killed by security forces.

Syria is a regional nexus, bordering five countries with which it shares religious and ethnic minorities and, in Israel's case, a fragile truce. Its web of alliances extends to Lebanon's powerful Hezbollah movement and Iran's Shiite theocracy. Turkey, until recently an ally, has opened its borders to anti-Assad activists and breakaway military rebels.

Mining the Lebanese border is a sign of the country's increasing isolation.

The crackdown has eviscerated Assad's reputation, canceling out widespread hopes when he took power in 2000 that he might transform his late father's stagnant dictatorship into a modern state. Instead, Assad has reverted to the same tactics that have kept his family in power for more than 40 years, using fear and brute military force to try to break the popular revolt against his autocratic rule.

Three residents of the Lebanese border village of Serhaniyeh showed an AP reporter a long sand dune barrier along the frontier where they said Syrian troops laid mines. Ahmed Diab, 26, said several trucks carrying about a 100 soldiers arrived in the area on Thursday and spent the entire day planting mines on the side of the barriers that is toward Lebanon.

"Since they planted the mines, no one dares to go to the border line," said Diab, as he sat on his motorcycle near his home that overlooks parts of the Syrian province of Homs. Homs has seen some of the worst violence of the uprising.

Many Syrians cross the border into Lebanon regularly, some of them to flee the violence in their country. And the mines are the latest in a number of signs that Syria is working to prevent Lebanon from becoming a safe haven for the Syrian opposition.

There have been at least three cases this year of Syrian dissidents being snatched off the streets in Lebanon and spirited back across the border, Lebanese police say. The abductions have raised alarm among some in Lebanon that members of the country's security forces are helping Assad's regime in its crackdown on anti-government protesters, effectively extending it into Lebanon.

Syria had direct control over Lebanon for nearly 30 years before pulling out its troops in 2005 under local and international pressure. But Syria still has great influence, and pro-Syrian factions led by the militant group Hezbollah dominate the government in Beirut. At the same time, Syria's regime is becoming increasingly more isolated internationally.

There also have been reports of Syrian troops crossing into Lebanon to pursue dissidents. In September, the Lebanese army said in a statement that Syrian troops briefly crossed the border and opened fire at people trying to flee the violence in Syria.

A senior Lebanese security official confirmed that Syrian troops are planting mines on the Syrian side of the border, but said Beirut will not interfere with actions on Syrian territory.

"What concerns us are violations of Lebanese territories and Syrian troops pursuits of people on the Lebanese side of the border," the official said on condition of anonymity in line with regulations.

Syria and Lebanon share a 230-mile (365-kilometer) long border, although it appears the landmines have been planted in Homs province -- where some of the worst violence of the uprising has occurred -- just across the border from Serhaniyeh, Lebanon. Mines also have been planted in the Baalbek region, which borders Homs and the Damascus countryside, witnesses say.

The crackdown has resulted in the most severe international isolation the Assad dynasty has seen. Sanctions from the European Union and the U.S. are chipping away at the beleaguered economy and many leaders have called on him to step aside. Turkey, until recently an ally, has opened its borders to anti-Assad activists and breakaway military rebels.

Assad has responded with defiance, exploiting fears at home and abroad of regional turmoil, sectarian violence and Islamic extremism.

In an interview with Britain's Sunday Telegraph published over the weekend, Assad warned world powers fresh from their victory over Muammar Qaddafi in Libya that the Middle East will go up in flames if there is any foreign intervention in his country.

Syria "is the fault line, and if you play with the ground, you will cause an earthquake," he said in his harshest words so far regarding the potential for foreign intervention. "Do you want to see another Afghanistan, or tens of Afghanistans?" he asked, alluding to the 10-year war that has bogged down tens of thousands of foreign forces.

But given that NATO and the U.S. have made abundantly clear they have no appetite for another military intervention in Syria, Assad does not have to worry too much about a Libya-style operation against his regime. Still, increased international focus on his bloody crackdown could bring more sanctions and isolation on a regime that is showing signs of increasing desperation.