An accusation of official involvement in cross-border terrorism has inflamed tensions between Tajikistan and Uzbekistan, two unevenly matched rivals for regional influence whose entrenched leaders have long jostled for the political high ground.

Relations between Dushanbe and Tashkent have been fraught by border skirmishes, espionage scandals, and back-biting since independence in 1991. But the suggestion that Uzbek authorities are exporting violence in an effort to destabilize Tajikistan represents a departure from the low-intensity squabbling of years past.

The head of Tajikistan's Supreme Court, Nusratullo Abdulloev, convened a press conference on July 16 to accuse Uzbek security forces of ordering an explosion that caused minor damage to the Supreme Court building in June 2007.

"The Uzbek National Security Service (SNB) planned the bombing in Dushanbe and through it hoped to disrupt stability and sow fear within the Tajik population," Abdulloev said, adding that the SNB works through "renegade former commanders from Tajikistan's civil war."

Abdulloev's appeal comes slightly more than a year after the sentencing of Komiljon Ishonqulov to 22 years in jail for his role in the overnight explosion, which caused no casualties but touched a raw nerve in a country still recovering from a bloody civil war in the mid-1990s.

Tajik officials say the Uzbeks have consistently ignored their requests for the handover of at least two other suspects in the case.

The court concluded that Ishonkulov had met with an SNB officer named Mirzoev Bobosubhon in Uzbekistan in the days before the explosion to put him in touch with an accomplice who accompanied Ishonkulov to Tajikistan to carry out the bombing. He added that the plan called for both men to flee to Uzbekistan after their work was completed but that Ishonkulov was detained before he could get across the border.

Abdulloev described Mirzoev as a former field commander from Tajikistan's Popular Front -- a paramilitary group that sided with the government during the 1992-97 civil war -- who is also a wanted criminal in Tajikistan.

Tajik authorities are convinced that Mirzoev's trail leads to a more odious figure in the eyes of the Tajik government: former Tajik Army Colonel Mahmud Khudaiberdiev, another former Popular Front commander. Tajik officials suspect that Khudaiberdiev and other ex-commanders continue to plot against Dushanbe, possibly from Uzbekistan.

A veteran of the Soviet conflict in Afghanistan, Khudaiberdiev led what was regarded as the best-trained and best-equipped unit in the Tajik armed forces at the outbreak of the civil war. After a peace deal was signed in 1997 to end the fighting, the colonel disappeared, along with much of his unit, only to return in November 1998 to attack Tajikistan's second-largest city, Khujand. Defeated, he vanished again -- but this time the trail led to Uzbekistan.

Dushanbe has demanded that Uzbek authorities hand over Khudaiberdiev and his fighters, but Tashkent has denied the colonel is on Uzbek territory.

Uzbek officials appear unlikely to answer Tajik requests to hand over any of the suspects Dushanbe is seeking in connection with the 2007 bombing, including Mirzoev or Khudaiberdiev.

"How many times have Tajik law enforcement agencies asked Uzbekistan, in accordance with bilateral agreements, to hand over the organizers of this crime and we have not received any answer, not even one letter?" Abdulloev protested.

As tensions have risen between Dushanbe and Tashkent, Uzbek officials have in turn accused Tajikistan of harboring members of the Al-Qaeda-linked Islamic Movement of Uzbekistan (IMU). Uzbek requests for those people to be handed over have similarly drawn denials or silence from Tajik authorities.

Ties between Tajikistan and Uzbekistan, marked by frequent flare-ups along their border, have been tense since independence in 1991.

Border guards frequently have shot across the frontier, injuring or killing people on the other side. Each side has accused the other's border guards of acting as lookouts or providing cover fire for thieves sneaking across the border to steal livestock or farm machinery. Each side has also tried and convicted citizens from both countries of espionage for the other.

Tajik President Emomali Rahmon and Uzbek President Islam Karimov have jousted over alleged incursions, and there appears to be little love lost between them. Karimov has intimated that his country's armed forces played a key role in Rahmon's rise to power during the mid-1990s.