By Patricia Vicente  Rua

Portugal's largest builder Mota-Engil is close to sealing a deal to sell a 30% stake in the company to China Communications Construction Co (CCCC), it said on Thursday.

In a statement, Mota-Engil said it was in the final stages of negotiating a deal that would value the company at around 750 million euros ($888 million) - about double its current market value - and involve a capital increase.

"Mota-Engil informs (...) that the counterparty of the strategic partnership and investment agreement in the last stages of negotiation is CCCC," it said.

The possible deal comes amid diplomatic pressure from the United States to encourage firms in Portugal and elsewhere in Europe not to rely on Chinese investment.

Mota-Engil shares spiked 22.9% in early afternoon trade to 1.78 euros, even as the company separately announced a first-half net loss of 5 million euros, compared with a profit of over 8 million a year ago.

As part of the proposed deal, Mota-Engil's controlling shareholder Mota Gestao e Participacoes SGPS (MGP) has "accepted to sell a relevant stake in Mota-Engil at a price that reflects a valuation which is high above the current market price", the company said.

Its market capitalisation was around 344 million euros before Thursday's jump.

The company said CCCC, which it described as one of the top five infrastructure groups in the world, would subscribe to "a relevant stake" in a share capital increase of up to 100 million new shares, and would end up with a total stake slightly above 30%.

MGP would own around 40% of the share capital, down from around 65% now.

Mota-Engil said the deal would boost its financial and other capabilities, allowing it to ramp up its activities in all markets and opening new opportunities.

($1 = 0.8450 euros)

(Reporting by Patricia Rua, additional reporting by Catarina Demony, writing by Andrei Khalip, editing by Mark Potter)