Twelve killed as bombers strike again in Russia

The blasts were in the province of Dagestan, where attacks occur almost daily along with Chechnya and Ingushetia, provinces in the North

Caucasus home of separatist Islamist insurgents.

"I don't rule out that this is one and the same gang," Prime Minister Vladimir Putin said.

The Moscow subway bombings that killed 39 people on Monday were the first suicide attacks in the Russian capital in six years and shocked a country that had grown accustomed to such violence being confined to its troubled southern corner.

They followed a recent warning from an Islamic militant leader that the militants would bring their struggle to the heart of Russia.

Yesterday's first bomber blew himself up when police tried to stop his car in the town of Kizlyar near Dagestan's border with

Chechnya. "Traffic police followed the car and almost caught up – at that time the blast hit," a police spokesman said.

As investigators and residents gathered around the scene of the blast, a second bomber wearing a police uniform approached and set off explosives, killing the town's police chief among others.

Nine police were among the dead from both blasts, authorities said. A school and police station nearby were also damaged.

Police and security services are a frequent target in part because they represent the Kremlin – the militants' ideological enemy – but also because of their heavy-handed tactics.

Police have been accused of involvement in many killings, kidnappings and beatings in the region, further alienating residents.

In January in Makhachkala, Dagestan's capital, a suicide bomber blew up an explosives-packed car at a police station, killing six officers. In August, 24 died and more than 200 were injured when a man crashed a bomb van into the police station in Nazran, Ingushetia.

The violence has continued despite Kremlin efforts. President Dmitry Medvedev, who recently said the militants had spread through the North Caucasus "like a cancerous tumour," this year appointed a deputy prime minister to oversee the troubled region and address the root causes of terrorism, including dire poverty and corruption.

Rebels from the North Caucasus were accused of masterminding the Moscow attack, but no claims of responsibility have been made.

Speculation has been rife that the attacks were retaliation for the recent police killings of high-profile militants in the North Caucasus.