Kazakhstan, which hosts Russia's Baikonur cosmodrome, is blocking three upcoming Russian satellite launches because of a dispute over the drop zone for rocket debris, reports said on Monday.

The first stages of the Soyuz rockets that were scheduled to launch a total of seven satellites were due to fall down over a region of north Kazakhstan that is only occasionally used as a drop zone for debris.

Kazakhstan argues that in order for the zone to be used the two sides must sign an additional agreement to the leasing accord it has with Russia, the Kommersant daily and Interfax news agency reported.

"Due to this we are simply unable to carry out not just our own but international obligations," a source in the Russian space agency Roscosmos told Kommersant.

The launches that are set to be shelved or already postponed are the launch of European meterorological satellite MetOp-B that had been due May 23, the launch of Belarussian, Canadian, German and two Russian satellites on June 7 and the launch of Russian satellite Resurs-P in August.

It is not clear how and when the seven satellites will now be launched.

There is no suggestion however that the dispute will affect manned launches from Baikonur which also use a Soyuz rocket but whose debris usually falls in a different zone.

Kommersant said one possible reason for the dispute is Russia's building of a new cosmodrome Vostochny in its own Far East territory which when completed will provide an alternative launch site to Baikonur.

It said Kazakhstan fears that the new cosmodrome will encourage Russia to break the lease agreement on Baikonur, which is due to last until 2050 and sees Moscow pay Astana almost $115 million in rent annually.

Baikonur was the historic Soviet cosmodrome from where Yuri Gagarin made the first manned space flight in 1961. Moscow kept control of the facility under an agreement with Kazakhstan after the collapse of the USSR.