Thai authorities on Monday sought to unravel the mystery of the ultimate destination of a plane that landed in Bangkok with a huge cache of weapons from North Korea, exported in defiance of a U.N. embargo on arms from the communist state.

Military analysts said the arms were likely destined for African rebel groups or a rogue regime like Myanmar.

Thai officials impounded the Ilyushin Il-76 transport plane Saturday and discovered what they said was 35 tons of explosives, rocket-propelled grenades, components for surface-to-air missiles and other armaments.

The plane's manifest had described the cargo as oil-drilling equipment, and the crew said the plane was supposed to deliver its cargo to Sri Lanka.

The United States, which is particularly concerned about North Korea selling weapons and nuclear technology in the Middle East, reportedly tipped off Thai authorities to the illicit cargo, according to Thai media reports that the government and U.S. Embassy declined to comment on.

Army Gen. Walter "Skip" Sharp, the top U.S. military commander in Korea, said in Washington that he was "not going to give away any of the intelligence as far as how we're watching to see what North Korea is doing up there."

Impoverished North Korea is believed to earn hundreds of millions of dollars every year by selling missiles, missile parts and other weapons to countries such as Iran, Syria and Myanmar.

U.S. Secretary of State Hillary Rodham Clinton praised the seizure, saying it "shows that sanctions can prevent the proliferation of weapons and it shows that the international community when it stands together can make a very strong statement."

Experts in the illicit arms trade said circumstantial evidence suggested the weapons were meant for Africa, which is a ready market rife with conflict.

The flight plan turned over to Thai police said the plane was registered to Air West, a cargo transport company in the former Soviet republic of Georgia, said Somsak Saithong, a lawyer for the arrested crew members.

He said the men, four from Kazakhstan and one from Belarus, insisted they were unaware they were transporting weapons. They were detained Sunday on a charge of illegal arms possession, which carries a penalty of up to 10 years in prison. A Thai court on Monday allowed police to hold them for at least 12 more days pending further investigation.

Giorgy Bokuchava, the head of Georgian transport administration, confirmed the plane belongs to Air West but said it was leased last month to the SP Trading, a company in Ukraine, another ex-Soviet nation.

A Russian deputy foreign minister, Alexei Borodavkin, praised the weapons seizure when asked by a reporter in Moscow.

"As shown by this case with the plane, which was detained in Thailand, these (United Nations) sanctions are working," Borodavkin said.

Thai government spokesman Panitan Wattanayagorn said the flight plan indicated the aircraft was headed for the Sri Lankan capital, Colombo.

However, investigations into weapons trafficking shows that documentation such as a flight plan "doesn't mean anything," said Siemon Wezeman, a senior fellow for the Arms Transfers Project of the Stockholm International Peace Research Institute.

The types of arms reported to be on the aircraft — intended to add firepower to defend against planes and tanks, which are usually in the arsenal of government forces — were typical of those used by insurgent movements, and raised suspicion that they could be headed for an African rebel group, Wezeman said.

Christian LeMiere, editor of the London-based Jane's Intelligence Weekly, said the range of the Il-76 and its apparent flight path suggested it may have been headed to Africa, where there are groups ready to buy North Korean weapons.

They included Sudan, which might pass the weapons to rebel groups in Chad, and Eritrea, which might keep them for its own arsenal or pass them on to warring factions in Somalia.

Wezeman doubted that Sri Lanka was the destination, because it already has a huge amount of weaponry on hand after its recently ended civil war.

Iran, though it is willing to defy the international community on issues of nuclear development, was an unlikely buyer because it makes its own weapons of the type seized, he said. But he acknowledged it was possible that the shipment was ordered by Iran for distribution to Hamas and Hezbollah.

In August, the United Arab Emirates seized a Bahamas-flagged cargo ship bound for Iran with a cache of banned rocket-propelled grenades and other arms from North Korea, the first seizure since U.N. sanctions were ramped up.

Myanmar, a pariah state known to have military links to North Korea, was also a possible destination, Wezeman suggested.

In July, a North Korean ship believed to be bound for Myanmar and carrying suspicious cargo, possibly illicit weapons, changed course and headed home after it was monitored for more than a week by the U.S. Navy.

The U.N. sanctions — which ban North Korea from exporting any arms — were imposed in June after the reclusive communist regime conducted a nuclear test and test-fired missiles. They are aimed at derailing North Korea's nuclear weapons program, but also ban North Korea's selling any conventional arms.

Smuggling weapons into African combat zones became a booming business in the 1990s, with warring groups funding their purchases through the sale of rare minerals and gems, including so-called "blood diamonds."

One of the biggest alleged figures behind the illicit arms trade in Africa is now in a Thai jail.

Russian national Viktor Bout was arrested in March 2008 in Bangkok after U.S. agents posed as arms buyers for the Revolutionary Armed Forces of Colombia, or FARC, which Washington classifies as a terrorist organization. The United States is seeking his extradition for trial on terrorism charges.

A Thai court in August rejected the extradition request, but Thai prosecutors have appealed the ruling.