Abu Dhabi's government-linked investment fund Aabar does not plan to buy any further shares in Daimler or a stake in Opel, a spokesman said.

Asked about a report that Aabar was raising its stake in Daimler, the spokesman said: 'We are not.'

Germany's Focus magazine said Abu Dhabi was in talks to raise its Daimler stake from 9.1 per cent now to more than 20 per cent.

Aabar also said it had no plans to invest in Opel, brushing off speculation the fund could make a white-knight appearance.

Earlier, the Aabar spokesman had already denied reports that the investment fund planned to take a stake in Opel, which is frantically seeking an investor.

General Motors' German unit Opel has said it needs 3.3 billion euros ($4.38 billion) in state aid from European governments to save jobs and keep plants open.

But it also said it needs an outside investor to push through its restructuring plan, and so far no one has publicly declared interest in Opel.

The ailing carmaker's rescue has become a political hot potato ahead of German elections in September as pressure mounts to help Opel, which traces its roots to the 19th century and was once a symbol of the country's post-war recovery.

On Monday, Economy minister Karl-Theodor zu Guttenberg had said he could not rule out talks with the emirate over Opel, but he later rejected reports there were concrete plans to travel to Abu Dhabi next week to talk to potential investors.

A German labour leader at the cash-strapped carmaker has confirmed the government of German state of North Rhine-Westphalia held talks with Abu Dhabi about Opel last week, but without naming the possible investors there.

Last month, Abu Dhabi's state-controlled International Petroleum Investment Company bought a 9.1pc stake in Daimler for almost 2 billion euros. It had at the time already said it was satisfied with its holding for now.