Russian Foreign Minister Sergei Lavrov said militants operating on the Afghan-Pakistan border may have helped organise suicide bomb attacks that killed 38 in Moscow yesterday, Interfax news agency reported.

Two female suicide bombers attacked Moscow metro stations during the Monday morning rush hour. Both likely had links to the North Caucasus, the centre of an Islamist insurgency against Moscow, the head of Russia's FSB state security service said.

Some Russian officials have said that the insurgents in the North Caucasus, which includes Chechnya, Ingushetia and Dagestan, have ties to al Qaeda, though many analysts have disputed the link.

Lavrov did not mention al Qaeda, but said the bombers may have had links to militants on the Afghan-Pakistan border, where al Qaeda militants, and Afghan and Pakistan Taliban fighters are present.

Asked if there could have been any foreign involvement in Monday's attacks, Interfax quoted Lavrov as saying: "I do not exclude that."

"We all know that the Afghan-Pakistan border, in the so called no-man's land, the terrorist underground is very well entrenched," Lavrov was quoted as saying.

"We know that many people there actively plot attacks, not just in Afghanistan, but also in other countries. Sometimes the trails lead to the Caucasus," he said.