General Motors has stepped up negotiation with rival suitors to offload a stake in Opel/Vauxhall, as talks with preferred bidder Magna International hit obstacles.

Financial Times reported RHJ International, a Belgium-based industrial holding company interested in Opel, has improved its earlier bid and GM was “taking it very seriously”, said a person close to the sale process, who added that a memorandum of understanding could be signed within days.

China’s Beijing Automotive Corp is also expected to present an improved offer shortly.

While Magna remains in pole position to sign a definitive sale agreement, talks have run into difficulties over access to GM’s global technology which Magna wants to secure on behalf of Russian partners.

If the sale proceeds, Magna plans to build Opel-based cars in Russia.

Some GM figures feel Magna is using its political backing to press for unfair terms.

GM also wants the right to buy back some or all of the stake.