Suicide car bombers struck a police station in Tajikistan on Friday, officials said, killing two officers and wounding 25 in an attack authorities blamed on a militant group linked to al Qaeda.

Tajikistan's first known suicide bombing in five years would deal a blow to the government of the ex-Soviet republic, where poverty pushes youth towards radical Islam and political rivalries still fester a decade after a civil war.

A sedan exploded after entering the courtyard of a regional police anti-organized crime unit headquarters in Khujand, Tajikistan's second largest city, Interior Ministry chief of staff Tokhir Normatov said.

The bodies of two police officers and the remains of two attackers were found in the debris from the blast, which badly damaged the building, Normatov told reporters in the capital, Dushanbe.

The Interior Ministry said the attack was likely carried out by the Islamic Movement of Uzbekistan, which aims to establish Islamic rule in ex-Soviet Central Asia and has fought alongside the Taliban and al Qaeda in Afghanistan.

But longtime President Emomali Rakhmon's government often blames the IMU for attacks, while his critics and rights groups accuse him of using the Islamist threat as an excuse to crack down on dissent in the nation of seven million.

Dosym Satbayev, a Central Asia analyst based in neighbouring Kazakhstan, said the bombing could have stemmed from internal power struggles with roots in Tajikistan's 1990s civil war.

It's possible it was connected to the tough policy Rakhmon has been conducting towards former field commanders and even former allies who helped him come to power, Satbayev said.

The government of Rakhmon -- wary of both Islamic militancy and political opposition -- has jailed 115 people this year on charges of belonging to banned groups, including at least 25 alleged members of the IMU.

The attack in Khujand came a day after Rakhmon fired most of the leadership of the country's security services following an August 23 jailbreak by 25 alleged Islamic militants accused of plotting to overthrow the government.

The prisoners, including four Afghan citizens and six Russians from regions plagued by an Islamic insurgency, killed five guards as they escaped from a Dushanbe detention centre.

A security service source said on Thursday that one of the escapees, a former inmate of the U.S. military prison in Guantanamo Bay, had been detained not far from Dushanbe.

Tajikistan has a porous 1,340-km (832 miles) border with Afghanistan in the south. Khujand is in the north, near the border with Uzbekistan, whose ties with Tajikistan are tense.

(Additional reporting by Maria Gordeyeva; Writing by Amie Ferris-Rotman and Steve Gutterman; Editing by Jon Hemming)