By Kevin Krolicki

DETROIT (Reuters) - Representatives of American Axle & Manufacturing Holdings (AXL.N: Quote, Profile, Research) and the United Auto Workers returned to the bargaining table on Monday for talks aimed at ending a two-week-old strike seen as increasingly costly for General Motors Corp (GM.N: Quote, Profile, Research) and other suppliers.

Monday marked the fifth straight day of bargaining between the two sides after talks broke down over the company's demand for steep wage concessions. Talks ran through the weekend and continued on Sunday past midnight, said American Axle spokeswoman Renee Rogers.

GM, which spun off American Axle in 1994 and relies on it for parts, has shut or partly shut almost 30 facilities employing over 37,000 workers in the United States and Canada because of component shortages triggered by the strike.

GM said 22 plants, including facilities in Michigan, Missouri, Wisconsin, Ohio, New York and Indiana, shut down or shifted to shortened work hours as of Monday.

GM has stopped or slowed work at eight assembly plants building its Chevrolet Silverado and GMC Sierra pickup trucks and also sport utility vehicles like the Hummer H2.

Analysts have said GM could be called in to help mediate the talks in a bid to move them toward a resolution that would allow it to avoid a more costly loss of production.

"These are most likely three-way negotiations and not just two-way talks," said IRN Inc. analyst Erich Merkle.

He added that the the longer the UAW strike against American Axle continues the riskier the situation for GM becomes. Although its own inventories of unsold vehicles provide it with a cushion, some smaller GM suppliers might be hard-pressed to ride out a prolonged work stoppage, he said.