Ministry spokesman Andrej Cirtek said the aircraft -- 16 Mi-171S helicopters and 10 Mi-35 attack helicopters worth a total 184 million dollars (150 million euros) -- would be delivered by the end of 2006.

The Czechs, who are members of NATO, will have to install technical equipment and communication systems in the helicopters.

In March, Prague and Moscow signed an agreement stipulating that around one fifth of Russia's outstanding debt to the Czech Republic could be paid in supplies of nuclear fuel, military equipment and electrical energy destined for re-export over the next two years.

Earlier this year the Czech defence ministry said it would request 29 combat helicopters -- 18 Mi-171s and 11 Mi-35s -- but in the end it signed an agreement for 26.

The military acquired seven Mi-35s, a new version of the Mi-24 helicopter, from Russia last autumn. The Mi-171 is an updated, better-equipped version of the Mi-17.

Inherited from the days of the Soviet Union, the Russian debt to the Czech Republic is part civil and part military. The former is managed by the finance ministry, the latter by the defence ministry.