Miller became prime minister in October 2001

Mr Miller has two fractured vertebrae but he will not need surgery, a doctor in Warsaw said.

Polish officials said at least eight others were also injured when the Soviet-era Mi-8 helicopter came down in a field just outside Warsaw.

A government spokesman said the aircraft had had an engine problem.

The doctor at Warsaw's interior ministry hospital, Grazyna Rydzewska, said Mr Miller was undergoing tests but his condition was "good".

"He has two broken vertebrae but without dislocation or pressure. His condition does not raise any serious concerns," she said.

The helicopter reportedly entered service in 1977

One of the injured - a woman civil servant - has a damaged lung and will have an operation, Polish media reported.

Mr Miller's spokesman Marcin Kaszuba told Polish television that the prime minister had "walked out of the helicopter unaided".

According to a witness quoted by Polish TV, the helicopter tilted sideways and clipped treetops before coming down.

Mr Miller and his delegation were flying back from southwestern Poland, where they had visited copper mines.

Mr Miller was originally scheduled to visit Ireland on Friday, ahead of Dublin's presidency of the European Union, which begins on 1 January.

Poland is set to join the EU next May.