By Roman Kozhevnikov
DUSHANBE (Reuters) - Tajik government forces fought supporters of a former warlord accused of murdering a security services chief, leaving more than 40 people dead on Tuesday in a remote eastern region on the border with Afghanistan, security services said.
The pre-dawn attack on fighters loyal to Tolib Ayombekov underlined the continuing instability in the impoverished former Soviet republic 15 years after the end of a civil war.
The assault took place three days after the regional head of the State Committee on National Security (GKNB) was found beaten to death.
Most communications were cut off in Khorog, capital of the autonomous region of Gorno-Badakhshan and the closest city to the fighting deep in the Pamir mountains.
Residents with secure Internet links told Reuters locals had been ordered to stay at home, government helicopters were flying overhead and gunfire could be heard in the distance.
The GKNB, successor to the Soviet-era KGB, said in a statement 12 servicemen and 30 rebel fighters had been killed. It said that troops had captured 40 fighters alive, including eight Afghan citizens.
"We are investigating whether the citizens of Afghanistan are involved with the Taliban, al Qaeda and the Islamic Movement of Uzbekistan," the statement added.
A senior security service source told Reuters on condition of anonymity that fighting had stopped for the night, but the operation had not yet been completed.
Tens of thousands of people died in Tajikistan, a mainly Muslim, Central Asian nation, during its 1992-97 civil war in which the Moscow-backed secular government fought a loosely aligned opposition that included many Islamist fighters.
Ayombekov, who has denied involvement in the murder, fought with the opposition during the civil war and was among the former fighters to receive government jobs in the peace deal that ended the conflict.
Tuesday's assault follows the murder on Saturday of Maj.-Gen. Abdullo Nazarov, head of the Gorno-Badakhshan branch of the GKNB. In an earlier statement, the GKNB accused Ayombekov of leading the "organized criminal group" accused of the killing.
Ayombekov's gang had for many years been involved in drug trafficking and the smuggling of tobacco and precious stones and had committed "bandit attacks", the GKNB said. It did not say why it had not arrested him earlier.
The security source told Reuters the murder of Nazarov was "the last straw".
"The warlord, who has clean forgotten that the war ended 15 years ago, must be destroyed," he said.
The people of Gorno-Badakhshan mainly supported the opposition during the civil war. Khorog is around 500 km (310 miles) southeast of Dushanbe, separated from Afghanistan by the Pyandzh river.
President Imomali Rakhmon has only a tenuous grip on the restive region and gangs regularly smuggle drugs, tobacco and other goods across the porous Afghan border.
Tuesday's operation appeared to be the largest of its kind since late 2010, when troops hit rebel forces in a retaliatory attack in the nearby Rasht valley region.
(Writing by Dmitry Solovyov and Robin Paxton, editing by Andrew Heavens)