Putin pledges to catch bombers

No one has claimed responsibility for the three atttacks

Russian President Vladimir Putin has sent the head of his federal security service and the prosecutor-general to the Caucasus region to lead the investigation into bomb attacks that killed at least 21 people and wounded more than 120.

The toughest measures will be undertaken to find and punish those who ordered and carried out these despicable murders

President Putin

In a message to grieving families, Mr Putin said extremely rigorous measures would be taken to find and punish those responsible.

"Only tough methods and harsh means can be used with these people. They don't understand any other language," he said.

The Kremlin has blamed Chechen separatists for the blasts, but a Chechen rebel leader said they were not responsible.

Mr Putin: Tough measures promised

Pledging to combat what he called terrorism, Mr Putin said:

"The international community understands how serious the events that are taking place are, and I am absolutely confident that we will put things in order eventually."

Death toll increases

The deadliest of the blasts happened in the town of Mineralnye Vody, where a car exploded in a crowded market.

Security officials there say the number of people killed has now risen to 19, with more than 100 injured, many of them seriously.

A simultaneous explosion wounded some 22 people near a police station in the town of Yessentuki, also in the Stavropol region.

Shortly after, two people died in a car bomb explosion in the region of Karachay-Cherkessia, according to Russian news agencies.

Reaction to Moscow

The Lada car exploded after police ordered it off the road and onto wasteland. They are reported to have found explosives in its petrol tank.

It's obvious that these were terrorist acts

Sergei Ivanov, national security adviser

No group has said it carried out the attacks, but President Putin's national security adviser, Sergei Ivanov, said they were probably a response by Chechen separatists to Moscow's efforts to restore order in the rebellious republic.

"The predictable and clear policies of the federal centre will make the leadership of the Chechen armed groups turn to the tactic of terrorist attacks, and not just in the territory of Chechnya. This is what is going on now," he said.

Suspect detained

Police are reported to have detained one suspect after the explosion in Mineralnye Vody.

The blasts appear co-ordinated

The Russian authorities say they have now stabilised Chechnya, having seized military control last year.

But attacks by Chechen separatists continue to take a heavy toll of troops stationed there.

A week ago suspected Chechen activists hijacked a Moscow-bound flight from Turkey to Saudi Arabia, demanding that Russia pull its troops out of Chechnya.

At the summit of European leaders on Friday Mr Putin defended Russia's operations against rebels in Chechnya and said the West would do well to follow Moscow's example against ethnic Albanian militants in Macedonia.