Disagreements over intellectual property rights have impeded progress of Magna's proposed takeover of Vauxhall/Opel.

The Sunday Times reports that GM does not want Magna to have the rights to use its technology outside Vauxhall and Opel.

Magna's main partners in its bid include Russian motor manufacturer Gaz, leading GM to fear that its technology could be used to build cars in Russia that would compete with its own products.

The report said that Magna and two other bidders, Beijing Automotive Industry Holding Company and RJH, will be asked to present their plans to the Barack Obama's automotive task force at the end of the month.