Clashes between government forces and troops loyal to former opposition warlord Tolib Ayombekov in the former Soviet republic of Tajikistan have left 20 soldiers dead.
Government security forces have been fighting Ayombekov soldiers in the country's remote eastern region, according to reports.
Communications have been cut off in the Gorno-Badakhshan's regional capital of Khorog.
"The battle is still raging," a senior security service source told Reuters. "Both sides are suffering big losses."
He said that security forces had seized a group of rebel fighters, including five Afghan citizens allegedly connected to the Taliban.
The BBC reported that people were trapped in their homes because of heavy fighting in the streets, which were being patrolled by armoured vehicles.
Dozens of people were reported wounded.
The GKNB, successors to the Soviet-era KGB, said an "organised criminal group" who stabbed to death intelligence officer Maj Gen Abdullo Nazarov on 21 July was led by Ayombekov.
The spy agency said that Ayombekov's gang trafficked drugs, tobacco and precious stones.
Tajikistan, the poorest of the ex-Soviet republics, is a 7.5 million-strong mainly Muslim country. It plunged into civil war soon after it became independent from the former Soviet Union in 1991.