Two people have died after an air ambulance helicopter en route to a multi-vehicle traffic pile-up crashed near Jarostow, in southwestern Poland.

A police spokesman said one injured person had been brought to hospital.

The accident occurred in thick fog, heavy cloud cover and snowfall, but the cause has not been determined.

The Soviet-era Mi-2 helicopter was headed to the scene of the traffic accident - involving more than 20 vehicles - to evacuate an injured pregnant woman.

It plunged to the ground about 12km from the site. Television footage showed it had crashed in a wooded area near several houses.

In late January, another Polish air ambulance, a Eurocopter EC-135, hired by the Turkish health ministry for medical airlifts, crashed in northwest Turkey, killing its two pilots. It was en route from Poland to Ankara.