BELGRADE, Sept 23 (Reuters) - Serbia, which is seeking investors for its ailing economy, has asked Chinese companies to bid for the concession to build, operate and maintain a key highway in the centre of the country, the government said.

Serbia's socialist-nationalist government needs to improve infrastructure to boost growth.

The economy is expected to grow about 2.5 percent this year but is weighed down by a rising budget deficit of 4.7 percent of GDP and debt seen at 65 percent.

Last year Serbia secured a 15-year, 850 million euro ($1.15 billion) loan from Beijing to build a road connecting the country to the E75 pan-European highway, with China Road and Bridge Corporation (CRBC) as the main contractor.

ID:nL5N0F71AH

Under a deal with a previous government, CRBC is also building a 170-million-euro bridge over the river Danube.

Belgrade is also seeking a low-interest, long-term loan from the United Arab Emirates to repay debts and invest in the economy. ID:nL5N0H919Y

Miodrag Jocic, a state secretary with the construction ministry, told Tanjug news agency that Chinese construction companies with annual turnover of at least 2 billion euros ($2.70 billion) over past three years will be allowed to bid for the concession on three stretches of a motorway in central Serbia.

Sections of the highway - linking Serbia with Romania and Montenegro - will be offered for concession of between 30 to 35 years, Jocic told Tanjug.

"Concessions may last for 50 years, but we will go for much shorter period," he said.

The deadline for the submission tender documents is set for Oct. 25, while applications to be opened on Oct. 28, he said.

Jocic said that only Chinese companies were invited to participate as China has investment funds for public-private partnerships and concession projects.

($1 = 0.7412 euros)

(Reporting by Aleksandar Vasovic; Editing by David Cowell)

((aleksandar.vasovic@thomsonreuters.com)(+381113044930))

Keywords: SERBIA CHINA