GENERAL Motors Corp, Ford Motor Co, and Chrysler LLC may be forced into bankruptcy by slowing economies and dwindling United States auto sales, Standard & Poor's analyst Robert Schulz said yesterday.

'Macro factors could overwhelm them at some point' even with the three biggest US auto makers committed to turnarounds,'' Schulz said in a Bloomberg Television interview.

S&P said on Thursday it may cut GM and Ford debt deeper into junk on forecasts for 2009 auto demand falling to the lowest since 1992.

GM, Ford and Chrysler are under pressure as the worsening global credit crisis makes it harder for buyers to get loans and dealers to finance their operations. US industry-wide sales tumbled 27 percent in September, the most in 17 years.

With all three companies working to boost cash, any bankruptcy filing would be a last resort, not a 'strategic' decision, said Schulz. 'We don't see that as something they would choose,' he said.

S&P said that its debt ratings for GM and Ford, already at six steps below investment grade at B-, may be lowered again because the auto makers faced a 'serious challenge' in 2009.

That prospect helped send GM to a 58-year low in New York trading on Thursday, at US$4.76, while Ford reached US$2.08 a share, its lowest since 1982. In early trading yesterday, GM slid to US$4.60 and Ford slipped to US$2.03. Chrysler was closely held.

GM would fall further, said Barclays Capital analyst Brian Johnson.

'With auto sales stalled in the US and beginning to contract in the rest of the world, we believe GM's cash needs are increasing,' Johnson said.

'Moreover, the downside risk of greater decline in worldwide auto sales driving greater cash needs is increasing,' he said yesterday.