Seven Russian border guards were killed and 13 wounded in Tajikistan when rebels launched an overnight raid on the frontier with Afghanistan, a border guards spokesman said on Friday.


It was the most serious blow in more than a year for the Russian force, policing Tajik borders under an agreement with the ex-communist government in Dushanbe. The Kremlin protested formally to Afghanistan.


The spokesman, contacted in the Tajik capital by phone, said the fighting started on Thursday at 8 P.M. Tajik time and subsided by 8 A.M. on Friday.


"In the course of the attack the rebels used mainly light arms," the spokesman said. "But they also shelled the border posts with missiles." Itar-Tass news agency quoted the Russian border guards commander in Dushanbe as saying the attack was preceded by two days of shelling both from Tajik territory and from Afghanistan, where the rebels found refuge after losing a civil war in 1992.


Russia agreed to keep its troops patrolling the border last year, declaring that it considered the Tajik frontier with Afghanistan as effectively Russia's own. Colonel Vladimir Novikov said around 500 rebels were involved in the overnight attack. He said the rebels were stepping up their attacks in an attempt to seize a strip of Tajik territory to announce the creation of a rebel government.


In a separate report from Tajikistan, Itar-Tass said 10 local policemen were killed and 20 wounded in a shootout with rebel forces 150 km (100 miles) east of Dushanbe on Thursday. Following the overnight attack, the Russian foreign ministry issued a protest to Kabul.


A statement quoted by Itar-Tass urged the Afghan government to ensure that its territory was not used as a base for "provocations" against Russian guards. The statement said Kabul would bear full responsibility for any consequences should such attacks continue.


In July 1993, more than 20 Russian border guards were killed in a rebel attack on the same border posts, prompting Russian promises to destroy any rebel installation on Afghan territory which they deemed threatening to the guards.


The 25,000-man Russian army has been active in the Central Asian state since the civil war which killed thousands, drove hundreds of thousands from their homes and ruined the economy. More than 10 Russian soldiers have been killed in the last three months in Tajikistan, many assassinated in the capital. Russian leaders have said frequently that their soldiers would not retreat from Tajikistan's frontier as long as an estimated 5,000 Afghan-based predominantly Islamic Tajik rebels kept up the fight.


Moscow has been pressing the Tajik government to reach a power-sharing deal with the rebels. But talks between the Tajik government and opposition, mediated by the United Nations and Russia, have brought no results so far.