Thousands of troops have surged into the remote Rasht Valley region near the Afghan border as part of a manhunt for militants believed responsible for a string of deadly attacks throughout the Central Asian state in recent weeks.

“Three fighters have been killed,” a Tajik military official said.

“Their identity has not yet been established but these fighters are from local terrorist organizations.”

A valley in Tajikistan has become the scene of a major security sweep following weeks of militant attacks that have fueled fears that violence may be spilling over from Afghanistan. Tajikistan has been on high alert for weeks amid terrorist blasts and a prison escape by insurgents and government opponents. A weekend ambush on a military convoy left at least 25 soldiers dead in a remote gorge along the Rasht Valley.

Radio Free Europe’s Tajik language service reported Thursday that it has received a video message from the Islamic Movement of Uzbekistan militant group claiming responsibility for the weekend attack.

Military vehicles rumbling through the valley have spread alarm among local residents, many of whom now fear a renewed descent into civil conflict. Over the past few days, truckloads of troops have been driving into these mountain towns daily and local people have reported seeing dozens of military helicopters flying overhead.

The government says it is seeking the arrest of former opposition warlord Mirzokhodzha Akhmadov, whom they accuse of organizing the terror attacks that killed two and wounded scores of others and of involvement in the ambush on the soldiers. Authorities also say Akhmadov is giving shelter to Mullo Abdullo, a leading militant who played a prominent role during Tajikistan’s five-year civil war.

Akhmadov also came to prominence during the 1992-97 civil war between President Emomali Rakhmon’s secular government and the opposition. Around 100,000 people were killed in the conflict, which made Tajikistan one of the poorest countries in the world.

As part of the peace deal that brought an end to the fighting, several major opposition figures - including Akhmadov - joined the government. Akhmadov led the anti-organized crime police department in the central Garm region until 2008. But President Emomali Rakhmon has methodically consolidated his grip on power and sidelined the former opposition, causing resentment and anger.

Akhmadov was accused in 2008 of killing a senior police officer on an inspection trip in Garm. In that episode, a team of police officers was attacked as they were heading to an official meeting that was to focus on the activities of Akhmadov.