BEIRUT — In his first interview since December, Syrian President Bashar Assad insisted Tuesday that his regime is fighting back against foreign mercenaries who want to overthrow him, not innocent Syrians aspiring for democracy in a yearlong uprising.

The interview with Russian TV showed that Assad still is standing his ground, despite widespread international condemnation over his deadly crackdown on dissent.

“There are foreign mercenaries, some of them still alive,” Assad said in an interview broadcast Wednesday. “They are being detained, and we are preparing to show them to the world.”

Assad also cautioned against meddling in Syria, warning neighboring nations that have served as transit points for contraband weapons being smuggled into the country that “if you sow chaos in Syria you may be infected by it yourself.”

He did not elaborate, but rebels and anti-regime activists said Syrian forces have mined many of the smuggling routes where weapons flow into Syria, mainly from neighboring Turkey and Lebanon.

Assad, who inherited power from his father in 2000, still has a firm grip on power some 14 months into a revolt that has torn at the country’s fabric and threatened to undermine stability in the Middle East.

The U.N. estimated in March that the violence has killed more than 9,000 people, and hundreds more have been killed since then as a revolt that began with mostly peaceful calls for reform transforms into an armed insurgency.

A group known as the Free Syrian Army is determined to bring down the regime by force of arms, targeting military checkpoints and other government sites.

A U.N. observer team with more than 200 members has done little to quell the bloodshed, and some even have been caught up in the violence themselves.

Six observers had to be evacuated from a town controlled by the opposition Wednesday, a day after a roadside bomb hit their convoy and left them stranded overnight with rebel forces. None of the observers was wounded, and it was not known who was behind the attack.

The shooting started as the convoy arrived in the opposition area, said Ahmad Fawzi, spokesman for international envoy Kofi Annan.

“The U.N. observers were in their cars and heard the shooting but did not witness anyone being killed, nor could they ascertain the direction of the fire,” he said. “At the same time, the bomb exploded near one of the vehicles, damaging the hood.”

When the shooting subsided, Fawzi said, the observers left their vehicles and proceeded on foot to a Free Syrian Army location where they spent the night.

Assad, 46, denies that there is a popular will behind the uprising, saying foreign extremists and terrorists are driving the revolt.

Al-Qaida-style suicide bombings have become increasingly common in Syria, and Western officials have said there is little doubt that Islamist extremists, some associated with the terror network, have made inroads in Syria as instability has spread.

The opposition described Assad’s claims as ludicrous, and said the regime’s attacks on peaceful protesters led many to take up arms.

“There are no foreign mercenaries in Syria,” said Rima Fleihan, a Jordan-based Syrian writer and activist. “The opposition doesn’t need them because people across Syrian provinces have taken to the streets. This is a revolution that is being made by the Syrian people.”

Assad has acknowledged that there are genuine calls for reform, although the opposition said he has offered only cosmetic changes that do little to change a culture where any whisper of dissent could lead to arrest and torture.