Decimated Forests Evidence of Thai Links to Cambodia : Asia: Logging exports are included in trade embargo against Khmer Rouge. Bangkok retaliates with ban on U.N. flights.

PHNOM PENH, Cambodia —  From the air, the area near Cambodia’s border with Thailand appears to have suffered a natural catastrophe. Almost all the trees are gone.

But then it becomes clear that the trees are lying by the sides of newly built roads, ready to be loaded into huge trailer trucks. Convoys of trucks haul the felled trees across the border into Thailand.

Dramatic aerial photos of the damage done to western Cambodia by Thai logging companies hired by the Khmer Rouge were shown to Western reporters by a diplomat requesting anonymity who observed, “The level of destruction is almost indescribable.”

The disclosure came as the U.N. Security Council imposed trade sanctions Monday against the Khmer Rouge for failing to live up to the October, 1991, Cambodia peace agreement, which called on the four factions in the country to disarm and demobilize their troops.

The council banned petroleum sales to areas controlled by the Khmer Rouge, as well as logging exports from those areas into Thailand. It also called on Cambodia’s governing Supreme National Council to ban gem exports.

In what appeared to be an early Thai reaction to the council vote, the Thai government Tuesday announced a ban on U.N. flights from Cambodia into Thailand, except for medical emergencies, a U.N. spokesman said. With 22,000 personnel based in Cambodia, the United Nations has used Thailand as a resupply point for its peacekeeping efforts.

While it has long been known that Thai companies were logging in Cambodia, aerial photos show a level of destruction that goes far beyond most estimates of U.N. officials.

The area around Pailin, the unofficial Khmer Rouge capital, has become a moonscape created by huge earth-moving machines used by Thai companies under contract to search for gemstones. Rather than look for gems in Cambodia, the companies scrape off thousands of tons of topsoil and take it to Thailand, where the search for gems will be carried out later.

Money from logging and gem mining is paid to the Khmer Rouge, which can buy arms and supplies on the open market in Thailand. Officially, all arms supplies to Cambodia’s four factions were to have been cut off last year.

Thai officials pleaded with the United Nations to avert sanctions, warning there is no effective means to police a border more than 500 miles long. But they also have said that U.N. police will not be allowed on the Thai side of the border because that would breach Thai sovereignty.

In part, this reflects Thailand’s interest in protecting its massive investment in western Cambodia, where an estimated 100,000 Thai workers are now engaged in the logging and gem trades.

One Thai mining company spokesman said Thai investment totaled more than $100 million at 200 mines under Khmer Rouge control. But diplomats said the Thais evidently believe that the Khmer Rouge, who ruled Cambodia in the 1970s, will be in power in western Cambodia for years and that they must strike a bargain with them to maintain security along the frontier.

It has been an open secret for years that Pol Pot, the hated Khmer Rouge leader who presided over the deaths of 1 million Cambodians during his 1970s reign, moves freely from Cambodia to Thailand, where he has a house and receives medical treatment.

Thai Prime Minister Chuan Leekpai has given assurances that his government will abide by any sanctions. But the Thai military, which controls the border and earns substantial revenue itself from border trade, has indicated it does not feel obliged to follow the sanctions.