ZAHEDAN Iran 20 Feb. (IPS) Heavy fog has forced rescue workers to call off for the night the search for wreckage of a military plane that crashed in south-eastern Iran, killing all 302 on board, officials said.

The 284 members of Iran's Islamic Revolutionary Guard and 18 crew- members on the plane were confirmed dead -- making the crash Iran's worst ever and one of the highest death tolls in aviation history.

Officials said the poor weather conditions made it dangerous for the workers to continue searching the rocky terrain where the Russian-made Ilyushin aircraft went down Wednesday evening.Iliyushin Il-76

More than 600 special mountain climbers as well as relief and search workers scoured the Sirch mount, partly in snow-capped slopes, only to find some of the bodies and part of the plane's debris, the official news agency IRNA said.

Kerman governor, Mohammad Ali Karimi, said snowstorm and gusts of strong winds on the peak had complicated retrieval of torn bodies.

"Weather condition in the crash site is such that visibility beyond one meter for climbers is impossible", he said.

Several helicopters, sent to the region for search and relief over flights, have failed to land on the crash site. Karimi said a road was being built with bulldozers to facilitate access to the bodies.

"Our main focus presently is on the construction of a road so that the forces can head to the most possible uppermost part of the mountain on cars," he added.

The Kerman governor said the cause of the crash still remained unknown and the possibility of finding the ill-fated plane's black box, which contains radio contacts between the pilot and air traffic controllers, was remote because of the bad weather.

"Twenty kilometres from the crash site, members of the bereaved families, huddled in mourning and waited in distress for emerging news. Three days of mourning was declared in Kerman", IRNA added.

The crash was the latest in a string of plane accidents the Iranian government has blamed on U.S. sanctions, arguing that they have prevented the country from repairing and replacing its aging fleet. Trade between Iran and the United States has been frozen under sanctions Washington imposed after the 1979 takeover of the U.S. Embassy in Tehran.

In December, Transportation Minister Ahmad Khorram acknowledged that Iran's air industry was suffering from U.S. sanctions on purchase of American-made planes and warned of air disasters if the trade ban was not lifted.

The minister, speaking days after the December 23 crash of a Ukrainian AN-140 plane that killed 46 scientists, said several of Iran's aging Boeing and Airbus planes had been grounded because of technical problems and lack of spare parts. He said Iran's fleet had "reached a crisis point".

This was the first time that an Iranian official publicly admitted that American economic embargo against Iran has so badly harmed the nation, as the official line is that the regime had been able to "rob the nose of the great US Satan to earth".

Washington cut off all ties with Tehran in 1979 after revolutionary Iranian students many of them now turned reformists and advocating normalisation of relations with the US stormed the American embassy in Tehran and took hostage 55 diplomats and staff as hostage.

Since the imposition sanctions, Iran has been forced to supplement its fleet of Boeing and European-made Airbus airliners with planes bought or leased from the former Soviet Union and analysts say there are difficulties obtaining factory-approved spare parts.

Iran is not allowed to buy European-made Airbuses because about 40 percent of their parts are U.S. made.

The aircraft, which crashed on Wednesday, went down in bad weather, just before the plane was due to land at the Kerman airport.

Officials said the pilot had complained of strong winds. His last words to the controllers were: "I am trying to approach the airport; maybe the weather conditions will get better". Then all contact was lost.

Officials refused to comment on why so many military personnel were travelling together?

The death toll exceeded that of Iran's previous worst air disaster in 1988, when an Iran Air A-300 Airbus was shot down over the Gulf by the U.S. warship Vincennes, which wrongly identified it as an attacking fighter. All 290 people on board were killed in that incident.

The crash came as Iran prepared to celebrate a religious holiday on Thursday to mark the day when Shi'ite Muslims believe the Prophet Mohammad appointed his son-in-law, Ali, as his spiritual heir.

The Iranian Cabinet has issued a message of condolence to the families of those killed in the crash, which was the latest in a series of aviation disasters in Iran, most of which involved Russian-designed aircraft.

A brief history of recent air crushes in Iran, involving Russian-made planes:

May 17, 2001 -- A Russian Yak-40 plane carrying 29 people, including Iran's Transport Minister Rahman Dadman and other deputy ministers crashes in northern Iran killing all on board.

Feb 12, 2002 -- An Iran Air Tours Tupolev-154 crashes near the western city of Khorramabad. All 119 people aboard are killed.

Dec 23, 2002 -- A Ukranian Antonov An-140 plane crashed into a mountain in central Iran, killing all 46 aboard. Most of the passengers were top Ukranian and Russian aerospace officials who were travelling to Iran to test fly an Iranian-built copy of the plane. The crash was blamed on pilot error. ENDS IRAN PLANE CRUSH 20203