General Motors says it is unable to comment on reports it will not have to pay US federal taxes on up to US$50bn of profits for 50 years.

The reports have been circulating in the US media and follow the manufacturer's announcement yesterday to go ahead with a US$13bn public share offering.

The IPO is a key part of plans to repay the US government's US$50bn bailout for the then bankrupt company in 2009.

However, a GM spokesman in the US told just-auto: "We are not in a position [to] make any comments on that."

A financial spokeswoman for GM also told just-auto the IPO announcement prohibited the company from making any further statements.

"We are under Securities and Exchange Commission guidelines and are not able to comment," she said.

"The IPO date has not been communicated yet - we can't comment on anything that is speculative."