KIEV (AFP) - Six people died, including suspected illegal migrants from South-east Asia, when an Mi-2 helicopter registered in Ukraine crashed in eastern Slovakia, the Ukrainian border guard said Friday.

"Two Ukrainian citizens and four nationals from South-east Asia, including two women, were onboard the civilian-registered helicopter, which crashed in Slovakia, 35km from the Ukrainian border," it said in a statement.

"It is likely that the helicopter was used by criminals to transport illegal migrants," it said.

Earlier, Slovak Interior Minister Robert Kalinak told reporters in Bratislava that the accident likely occurred on Wednesday - when the helicopter crossed the border - but rescuers only discovered the wreckage near the eastern city of Michalovce on Friday because of thick fog.

Kalinak said the aircraft likely tried to evade Slovakia's air traffic control system: "It was performing dangerous manoeuvres."

Slovak media reported that the helicopter's passengers likely included smugglers of cigarettes, which cost less in Ukraine than in Slovakia.