It was fast, 'Miami Vice' style

Joao Souza, Police spokesman

The two men were serving sentences for murder and bank robbery.

The BBC's correspondent in Brazil, Jan Rocha, said escapes from Brazil's overcrowded and violent prisons have been happening on an almost daily basis.

Armed hijack

The spectacular operation began when two men walked into an air taxi hangar at the airport in Sao Paulo and hired a helicopter saying they wanted a panoramic ride over the city.

Soon after take off though, they drew guns and ordered the pilots to fly to the Guarulhos prison.

The prison is surrounded by four sets of walls manned by armed police, but the helicopter landed in the central yard where prisoners were queuing for their lunch and two of the inmates scrambled aboard.

"The helicopter landed in the exercise yard and carried away two prisoners who are still at large," the Sao Paulo Prison Administration Department's spokeswoman, Rosangela Sanchez said.

Helicopter abandoned

"It was fast, 'Miami Vice' style," said Guarulhos military police spokesman Joao Souza, referring to the popular 1980s television police television series "Miami Vice."

Police guards shot at the helicopter but it lifted off and was later found abandoned, full of bullet holes on a soccer field near the town of Embu das Artes, about 50 km from the city.

Local media reported that the inmates had been whisked away in a white van.

The pilot was released unharmed and police are now hunting for the escaped prisoners, law enforcement officers said.

In Rio de Janeiro last year a bulldozer was used to break down the wall of a prison and release inmates, while over 100 prisoners escaped from Sao Paulo's huge Carandiru prison through tunnels dug under the walls.

The most sophisticated escapes are organised by specialised gangs who work for the criminal organisations to which many of the prisoners now belong.