A dramatic escalation of the war against Islamist rebels in Dagestan has placed President Yeltsin and his supporters under severe pressure in the buildup to elections for the State Duma in December.
On Saturday, a massive bomb exploded in a military apartment block in the Dagestani city of Buinaksk. Russian NTV reports that the death toll may reach 50.
Soon afterwards more than 2,000 rebels poured into the region from Chechnya.
There were reports last night that Russian units had been surrounded and that a state of "total mobilisation" had been declared in the region.
The events, allied to strong speculation in Moscow political circles that Mr Yeltsin may announce his early retirement from the presidency, have added to the already volatile situation in Russia.
Russian voters were given stark reminders of the disastrous Chechen war yesterday with reports from the town of Buinaksk where the five-story apartment building was almost completely destroyed by what appears to have been a huge car bomb. The building was used to house officers of the Russian armed forces, many of them Muslim Dagestanis, and their families.
TV reports showed distressed relatives of the dead and injured, many of them women in headscarves in the Muslim style, in tears at the scene of the explosion as hundreds of relief workers searched from survivors in the rubble. The workers paused from time to time to demand silence in the hope they might hear sounds indicating life.
The explosion took place at 9.40 p.m. on Saturday night when most of the soldiers were watching a European championship football match between Ukraine and France.
Shortly after the blast a truck with one tonne of explosives was apprehended near another military apartment block in Buinaksk.
In the early hours of yesterday morning, more than 2,000 Islamist rebels poured across the frontier from neighbouring Chechnya and captured a number of villages in an area of Dagestan which has a significant Chechen population.
The Russian NTV station last night reported that two major units of Russian interior ministry forces, one from the Black Earth Region city of Lipetsk and the other a local group from Dagestan, had been surrounded by rebel forces under the leadership of the Chechen warlord, Mr Shamil Basayev. A deputy interior minister, Mr Igor Zubov, said he was confident that federal troops would be able to come to the aid of the trapped soldiers.
Fighting in Dagestan began on August 7th when Mr Basayev's guerrillas, invariably described as "bandits" by the Russian media, crossed the frontier. The rebels are mainly members of the ultra-strict Wahhabi sect of Islam which originated in Saudi Arabia and has few indigenous supporters in the region. Some of the fighters are believed to come from outside the Russian Federation and one of their commanders, known only as Khattab, is believed to be a Jordanian.
The pro-rebel news agency, Kavkaz-Tsentr, yesterday claimed that the towns of Lenin-Aul and Kalinin-Aul had been captured by the "Dagestani Mujahideen" from what it described as the "Russian Kaffirs".
The explosion of violence in the northern Caucasus is bad news from Mr Yeltsin and his latest prime minister, Mr Vladimir Putin. A victory over the rebels had been expected to boost Mr Putin's chances of replacing Mr Yeltsin as president when elections are held next summer. It would also have been of assistance to the pro-Yeltsin groups running in December's elections for the State Duma .
With his health still poor, allegations of personal corruption on the increase and the arrival on the political scene of the powerful, non-communist opposition grouping, Fatherland-All Russia, Mr Yeltsin's hold on power is at his weakest since he took office eight years ago. Many analysts now suggest that he will soon retire and allow presidential elections to be held jointly with the Duma elections on December 19th. The argument is that opposition groupings would be given less time to organise. If there has been a single consistent trend during Mr Yeltsin's presidency, however, it has been his determination to hold on to power. It would be extremely difficult for his supporters to persuade him to step down.
The independent Russian news agency, Interfax, reported last night that the international Islamic activist, Mr Osama Bin Laden, had visited Chechnya and spent some time at the "Said ibn Abu Vakas" training camp in the Chechen village of Serzhen Yurt where rebels were trained by 40 "experienced" instructors mostly from the middle east but also from Russia, Ukraine and the Baltic countries.
Reports from Dagestan usually come with either a pro-Russian or a pro-Chechen slant.