Filing for bankruptcy would allow General Motors to reduce its debt more aggressively than an out-of-court restructuring and might not be as damaging as it would have been just a few months ago, an analyst has said.

"We think the damage to the enterprise of a GM bankruptcy today is notably less than it would have been a few months ago, largely because of public desensitisation to a bankrupt carmaker," JP Morgan analyst Himanshu Patel said in a client note for clients cited by Reuters.

The news agency said Patel's note raised the possibility - by a prominent Wall Street analyst - of the renewed threat of GM or Chrysler bankruptcy, a risk many observers believed had been sharply reduced by the government bailout.

GM and Chrysler are working to a 17 February deadline by which they must submit new restructuring plans to the US government as a condition of the US$17.4bn federal loans they received recently.

According to the report, GM has said it is aiming to reduce its unsecured US debt by about two-thirds from nearly $28bn to $9bn and also plans to halve the $20bn it has promised to a health care trust fund affiliated with the UAW by offering equity instead of cash.

But Patel was quoted as saying the diminished threat of a bankruptcy filing by GM appeared to have removed a key incentive for bondholders to offer concessions.

"After the GM bailout, GMAC received aid, GMAC received bank holding status without achieving required funding levels (and) Chrysler and its (financing company) received aid," Patel said. "All of these steps by the government were likely to have emboldened bondholders."

Patel said that if GM fails to win substantial concessions from bondholders and the UAW, the bailout could become "a political lightning rod" for the Obama administration, Reuters reported.

"We are increasingly thinking that such a development might force the White House to more seriously consider allowing GM/Chrysler to go into bankruptcy," Patel said in his note.

The report noted that GM has repeatedly ruled out seeking bankruptcy protection, saying such a step would scare off consumers, cause its revenues to plummet and risk that a Chapter 11-style restructuring would end up as a liquidation of its assets.

But some critics of the US bailout for the auto industry have said that the government could provide bankruptcy financing for GM or Chrysler and allow them to win deeper concessions from creditors and the union.

Reports on Monday said the US Treasury had retained two law firms with extensive bankruptcy experience and the investment bank Rothschild to advise officials on the taxpayer-backed restructuring of GM and Chrysler. One of the scenarios those advisers would consider would be a government-assisted bankruptcy filing, a person with direct knowledge of the work has said.

Another immediate priority would be working out an agreement between other creditors and the government that would provide senior status to the public funding, a second person involved in the discussions has said.

JP Morgan's Patel said a GM bankruptcy filing would likely cut the automaker's debt by over 60% compared with just 25% under an out-of-court restructuring, the report added.