LISBON (Reuters) - The European Commission has approved a takeover bid by Spain's Caixabank (>> CaixaBank SA) for Portugal's Banco BPI (>> BANCO BPI), paving the way for the Spanish bank to register the offer formally with regulators.

The Commission said on Tuesday it had approved the bid after concluding that the proposed acquisition would raise no competition concerns because the companies' combined market shares are very low.

Caixabank has said it was waiting for the European approval before registering the bid, which would have a big impact on Portugal's banking sector, where BPI is the second-largest listed lender. The Spanish bank's bid has been contested by BPI's second-largest shareholder, Angolan investor Isabel dos Santos.

The bid still needs the European Central Bank's consent, according to BPI Chairman Artur Santos Silva.

Caixabank, which is already BPI's largest shareholder with a 44.1 percent stake, launched the bid for all of BPI in February at 1.329 euros (97p) a share.

Dos Santos, with an 18.6 percent stake, is opposed to the bid and has proposed a merger of BPI with its largest competitor, Millennium bcp, instead.

The BPI board has rejected Caixabank's bid as too low, arguing that it does not reflect the bank's real value.

On Monday, Millennium bcp said it was ready to talk to BPI about a friendly merger but it depended on BPI's willingness, which in turn hinges on whether it accepts Caixabank's offer.

(Reporting By Axel Bugge, editing by Andrei Khalip and Jane Merriman)

Stocks treated in this article : BANCO BPI, CaixaBank SA