Slovakia has switched on a re-equipped nuclear power station despite opposition from neighbouring Austria and environmental groups.

Officials at the Mochovce nuclear plant -- about one-hundred-and eighty kilometres east of Vienna -- say they have started the first reactor, which is expected to become fully operational next month.

They rejected allegations that the plant -- an upgraded Soviet design -- is unsafe.

However, the Austrian head of a team that inspected Mochovce last month said he greatly regretted the move to activate it, which has also been strongly condemned by the environmental group, Greenpeace.

Austria had earlier warned that starting up the nuclear plant could damage Slovakia's hopes of joining the European Union.