Investigators confirmed Wednesday that at least two non-crew members were in the cockpit of the plane carrying late Polish President Lech Kaczynski before it crashed last month.

Tatyana Anodina, the head of the inter-state committee that investigates plane crashes in the former Soviet Union, said investigators had been able to rule out terrorism, technical failure and explosion as causes of the crash, which killed all 96 people on board.

"It has been established that in the cockpit there were individuals who were not members of the crew," said Anodina. "The voice of one of them has been identified exactly; the voice of the other, or the others, will require additional information from the Polish side."

Anodina did not comment on the name of the identified person, but Polish news agency PAP quoted an anonymous source close to the investigation as saying that one voice belonged to Polish Air Force Commander in Chief Andrzej Blasik.

The Polish representative to the investigative committee, Edmund Klich, said the non-crew members were in the cockpit 16 to 20 minutes before the crash.

Klich said that after listening to the cockpit recordings, he did not believe that the pilots were pressured to land.

Poor weather conditions

Investigators said that the crew of the TU-154 airplane had been warned of poor visibility - just 200 meters (218 yards) - four minutes before it crashed into the ground outside the Russian city of Smolensk. They determined that the plane was carrying ample fuel for the flight or onward travel to back-up airports.

But the crew ignored warnings from the control tower and from the crew of a Polish air force Yak-40 which had landed earlier that day.

"The air traffic controller at Smolensk Severny airport... twice warned the crew that there was fog at the airport, visibility was 400 meters (440 yards) and the conditions were not present to receive the plane," said Alexei Morozov, head of the committee's technical commission.

Tragedy after tragedy

Kaczynski, his wife and dozens of other political leaders and government officials were killed en route to a memorial service commemorating the 1940 Katyn massacre, in which 22,000 Polish troops and members of the intelligentsia were murdered by Soviet forces in and around the Katyn forest outside of Smolensk.

For decades the Soviet Union had blamed the killings on Nazi soldiers, but the April memorial had been expected to ease tensions between Poland and Russia. In the aftermath of the crash, the outpouring of sympathy from the Russian side and an increased willingness to release information about the massacre has led to reconciliation between the countries.

svs/AFP/dpa/Reuters
Editor: Martin Kuebler