By Gareth Jones
WARSAW (Reuters) - The Polish president's funeral looked set on Friday to go ahead as planned this weekend at his family's insistence despite a cloud of volcanic ash that has shut Europe's airports and may prevent world leaders attending.
U.S. President Barack Obama is among dozens of leaders scheduled to travel to Krakow in southern Poland for Sunday's funeral of President Lech Kaczynski and his wife Maria, killed with 94 others in a plane crash in Russia last Saturday.
Tens of thousands of mourners continued to file past the Kaczynskis' coffins in Warsaw's presidential palace on Friday. Some had been waiting up to 18 hours to view the coffins, a measure of the grief felt by many Poles over the worst single disaster to strike their country since World War Two.
The heads of Poland's armed forces, its central bank governor and opposition lawmakers also perished when their ageing Tupolev plane crashed in thick fog while trying to land near Smolensk in western Russia.
Warsaw's picturesque Old Town, where the palace is located, has been transformed into a shrine for the dead, festooned with flowers, candles, crucifixes and white and red national flags.
The funeral plans hit an unexpected snag on Friday when the volcanic ash cloud drifting over Europe from Iceland forced the closure of airports, including in Poland, stranding hundreds of thousands of travellers.
"I wish to say that the (Kaczynski) family's will is that the date of the funeral should not be postponed under any circumstances," presidential aide Jacek Sasin told reporters.
Earlier, Sasin had signalled the funeral might be delayed by Iceland's volcanic eruption and the disruption of air traffic.
POLARISING FIGURE
As well as Obama, Russian President Dmitry Medvedev, German Chancellor Angela Merkel, French President Nicolas Sarkoy and Britain's Prince Charles are among dignitaries from an estimated 96 countries expected to attend the funeral.
Krakow's Balice airport, due to handle most arrivals, shut down on Friday because of the volcanic ash cloud, which has caused air traffic disruption across northern Europe on a scale not seen since the September 11 attacks in 2001.
Volcanic ash contains tiny particles of glass and pulverised rock that can damage engines and airframes. Experts say the ash could cause problems to air traffic for up to six months if the eruption continues.
The decision to bury the Kaczynskis at Wawel, usually reserved for Poland's kings and national heroes, was already controversial. Some Poles believe Kaczynski does not deserve such an honour and have staged noisy protests against the move.
Public support for Kaczynski, a polarising nationalist and eurosceptic, had dwindled to just 20 percent before his death. Polls showed he would have lost to Bronislaw Komorowski, the candidate of Prime Minister Donald Tusk's centrist Civic Platform (PO), in a forthcoming presidential vote.
Komorowski, who is also speaker of parliament, became acting president after Kaczynski's death. It is unclear who will now be his main rivals in an election likely to take place on June 20.
Kaczynski was the candidate of his twin brother Jaroslaw's right-wing Law and Justice (PiS). The candidate of the main leftist opposition party SLD also died in the crash.
Kaczynski and his entourage had been travelling to mark the 70th anniversary of the massacre of some 22,000 Polish officers by Soviet forces in Katyn forest -- an enduring symbol for Poles of their country's suffering -- when their plane crashed.
The exact cause of the crash remains unclear, though Russian officials say the pilot ignored advice from air traffic controllers to divert to another airport because of the fog.
Some Polish media have speculated that Kaczynski, in his determination not to miss the Katyn event, may have ordered the pilot to try to land the plane against the Russians' advice.
On Thursday, Polish prosecutors promised to release details of the plane's cockpit voice recorders which are being analysed.
(Additional reporting by Gabriela Baczynska and Pawel Florkiewicz in Warsaw, Amie Ferris-Rotman in Moscow)
(Editing by Elizabeth Fullerton)
