Germany's economy minister Karl-Theodor zu Guttenberg is to visit Abu Dhabi to evaluate the possibility of the Gulf emirate taking a stake in Opel, media reports said.

German newspaper Handelsblatt said Guttenberg might visit Abu Dhabi as early as next week, according to Reuters.

On Monday, press reports said Abu Dhabi's royal family might invest in Opel and Guttenberg was quoted as saying that talks with the emirate over Opel could not be ruled out.

A German government spokeswoman told the news agency the economy ministry had no comment to make on the latest Handelsblatt report but referred to Guttenberg's Monday comment about Opel.

Reuters noted that GM Europe president Carl-Peter Forster told German weekly magazine Der Spiegel on Saturday that private equity firms and sovereign wealth funds have shown interest in the business. "We are speaking - for example - with interested parties from the private equity sector and with sovereign wealth funds," Forster was quoted as saying.

GM has warned of a looming liquidity crisis at Opel and UK subsidiary Vauxhall and has asked European governments for EUR3.3bn in loans and guarantees, of which EUR2.6bn is needed for Opel.

Opel Bochum plant works council chief Rainer Einenkel on Monday confirmed earlier media reports that the German state of North Rhine-Westfalia had held talks with Abu Dhabi on possibly investing in the unit, Reuters said.

He added he would not object to Abu Dhabi becoming a shareholder.