MOSCOW (Reuter) - At least seven Russian police died when their vehicle was blown up near Chechnya on Tuesday and a French aid organisation said one of its workers had been kidnapped, the third foreigner abducted in the area in a week. Five Chechens were also seized on Tuesday from a bus on its way to Chechnya from the Caucasus region of North Ossetia. The separate incidents raised tensions in the region after a period of relative calm and an apparent improvement in relations between Chechnya`s separatist leaders and Moscow, which fought a bloody military campaign against them in 1994-6. A spokesman for Medecins sans Frontieres (MSF) said unknown kidnappers had taken Christophe Andre hostage from MSF headquarters in Nazran, during the night of July 1 to July 2. Nazran is the capital of Russia`s north Caucasus region of Ingushetia which borders Chechnya, where two British aid workers were abducted last week. Many Chechen refugees still live there. In Dagestan, which also borders Chechnya, a bomb went off on Tuesday morning under a truck carrying police assigned by Moscow to guard the frontier with the breakaway republic. A Dagestan interior ministry spokesman told Reuters seven of them had died and 13 were taken to hospital but Russian news agencies later put the death toll at nine. For his part, Chechen President Aslan Maskhadov has said Russia is trying to blockade his region, which insists it is independent despite a peace deal last year putting off the issue of sovereignty for five years. In a sign of improved relations, Moscow and the separatists signed a memorandum on transporting oil across the region last month and have been discussing banking and customs agreements. But a final deal on the oil pipeline, part of multi-billion dollar project to extract oil from Azerbaijan and transport it to western markets, has yet to be signed. Maskhadov, who is planning special measures to free the captives, said in a statement on Tuesday the kidnappings were a provocation aimed at destabilising the region by people wanting to disrupt the fragile peace established in August. Maskhadov said the same people were behind both abductions. "They are links in the same chain and the work of those forces trying to obstruct the building of an independent Chechen state," he said. Two Britons working for another aid organisation were kidnapped in Chechnya last week. The Chechen authorities are investigating but there has been no word of their whereabouts or of demands by the kidnappers, who normally seek huge ransoms.