* Latest attack in Russia's volatile North Caucasus
* Russia fighting escalating Islamist insurgency
* Analysts say attacks likely to continue
(Updates death tolls, adds comments, details from scene)
MAKHACHKALA, Russia, Jan 6 (Reuters) - A suicide bomber killed at least seven policemen and wounded another 20 people on Wednesday in Russia's southern region of Dagestan by detonating a car packed with explosives at a traffic police depot.
Russia is fighting an escalating Islamist insurgency in the North Caucasus and President Dmitry Medvedev says the upsurge of violence over recent months is the country's single biggest domestic problem.
The suicide bomber tried to drive a Neva car packed with explosives into a traffic police depot at 0755 (0455 GMT) on the outskirts of Dagestan's capital, Makhachkala, but was rammed by a police UAZ jeep before detonating the explosives.
"The police spotted the suspicious car and rammed it from the side after which the explosion took place," a police spokesman said, adding that the policemen who rammed the car were killed in the resulting explosion.
Windows were blown out over 200 metres (650 ft) away by blast which left a 2.5 metre (8 ft) wide crater in the ground and dozens of police cars lay mangled at the depot.
Bomb experts from Russia's domestic intelligence agency, the Federal Security Service (FSB), said the bomb was equivalent to about 50-60 kg (110-130 lb) of TNT, an FSB spokesman said.
The patchwork of republics along Russia's southern flank have seen a wave of attacks over the past year that leaders say are fuelled by a potent mixture of clan feuds, poverty, Islamism and heavy-handed tactics by law enforcement agencies.
After Wednesday's blast, Medvedev ordered the Interior Ministry and the FSB security service to toughen security in Dagestan, the Kremlin said.
ATTACKS ON THE RISE
The growing turbulence has raised concerns that violence could spread from the mainly Muslim North Caucasus to the major cities of the Russian heartland.
A similar suicide attack on a police station in Ingushetia last August, killed 25 people and wounded at least 200 others. After that attack local police chiefs were fired by the Kremlin for failing to prevent the attack.
"This attack could have been much more deadly so I consider this a success for the police that the death toll was so low," said Grigory Shvedov, editor-in-chief of the 'Caucasian Knot' www.kavkaz-uzel.ru Internet news agency.
"But these suicide attacks are going to continue," said Shvedov.
Medvedev said last year that poverty, endemic corruption and widespread despair were driving young men from Dagestan and Ingushetia into the hands of Islamist rebels, who say they want to turn the region into a sharia state independent of Russia.
Critics say the Kremlin's North Caucasus policy is in tatters after years of throwing oil money at the regions while using the security services to crack down hard on militants, and warn that the situation in the region is swiftly deteriorating. (Writing by Guy Faulconbridge, editing by Jon Boyle)
- Reuters - Thomson Reuters Foundation
- For more humanitarian news and analysis, please visit https://www.trust.org/alertnet