"GM told us that it submitted the letter by fax," said spokesman Lee Chang-won at Daewoo Motor, which submitted a separate letter of intent to participate in the bidding for Kia Motors and its sister Asia Motors Corp.

GM faces at least four competitors, among them Ford Motor and three Korean suitors -- Hyundai Motor, Daewoo Motor and Samsung Motors Inc -- who have formally submitted letters of intent to acquire both firms.

Italy's Fiat SpA has also thrown its hat into the ring, the Chosun Ilbo newspaper reported. GM is negotiating a strategic alliance with Daewoo, the spokesman said.

"GM, in talks with Daewoo for a strategic business alliance, informed us of its decision as we had also let GM know our bidding," the spokesman added.

Officials at Kia Motors and Andersen Consulting, a US consulting firm organising thebidding process, declined to comment on bidders.

"The international bidding was closed by Friday's deadline as scheduled. We cannot say which companies had participated in the bidding as bidders don't want their names to be disclosed," said an official at Andersen Consulting.

Korea Development Bank (KDB), Kia's main creditor, had said it would sell Kia and Asia Motors as one deal because of their complementary relationship.

A Kia Motors spokesman said earlier on Saturday six automakers including three foreign carmakers were vying to take over the Korean companies. But later he said his company was not sure how many foreign companies had applied. Chosun Ilbo newspaper said Fiat SpA also sent a letter to take part in the bidding. Analysts said the firms offered an attractive opportunity for companies aiming at a foothold in the Chinese market. "If some debts will be written off, it's a good opportunity to buy a carmaker with one million units production capacity at reasonable price," said Rhee Namuh,executive director at Samsung Securities. "Kia will provide a good platform to foreign carmakers to advance into Chinese market," he said. KDB said Kia's total liabilities were estimated at 8.75 trillion won ($6.83 billion) at the end of March, against assets of 7.72 trillion won.

Asia Motors had 3.07 trillion won of liabilities, compared with 1.64 trillion won of assets.

A KDB official said creditors were discussing writing off some of the debts of the two automakers and the decision would be announced early next week.

No details were given. Analysts said the prospect of union problems would prompt foreign and Korean carmakers into active joint ventures to take over the two companies, even though no bidders made this clear in their letters.

"Foreign carmakers would not take a risk to run Kia alone because of union problems in Kia," said Lee Sangyong, an car analyst at KEB Smith Barney Securities. "If a foreign firm will do (it), its initial investment will be enormous."

The bidding would mostlikely boil down to a battle between the GM-Daewoo and Ford-Samsung consortiums. "Kia can be a good target for GM's global strategy. I believe GM will eventually join hands with Daewoo. And the team will have the best chance to win the bidding," he said. Lee Chang-won at Daewoo Motor said: "We will keep all channels open with GM and Hyundai for various kinds of strategic alliances.

"Official at Daewoo and Hyundai had said they would cooperate to take over Kia. But analysts said Daewoo would benefit more from GM than from Hyundai as creditors and the government hoped the Kia deal would lure foreign funds.

But analysts said Samsung might not be able to strike a deal with Ford, since the upstart Korean automotive firm has little to offer the UScarmaker, and would face a large sacrifice in any tie-up. Samsung said it was forming an international consortium to participate in the bidding but gave no details. Kia creditors will meet the bidders on Monday to explain the details of the two companies' financialstatus and will announce a winner on September 1 after a 10-day review of formal bid applications, to be submitted by August 21.