Heading to China, Turkey's Erdogan eyes improved missile defence bid

* Turkey chose Chinese firm as preferred candidate

* NATO allies concerned over compatibility

* Diplomatic row over Uighurs hangs over Erdogan visit (Adds quotes, details on bid process)

By Tulay Karadeniz

ANKARA, July 28 (Reuters) - Turkey is open to an improved offer from preferred bidder China in a long-range missile defence system tender, President Tayyip Erdogan said on Tuesday ahead of a visit to Beijing, reviving a deal that has raised security concerns among NATO allies.

Erdogan's state visit to China is expected to focus on Turkish trade links with the world's second-biggest economy. But a recent diplomatic spat over the treatment of China's Muslim minority Uighurs will also loom over talks.

NATO member Turkey chose China Precision Machinery Import and Export Corp in 2013 as the preferred candidate for the $3.4 billion deal, stirring U.S. and Western concern about security and the compatibility of the weaponry with NATO systems.

The agreement with China then languished, and Turkey re-opened negotiations with U.S. and European firms over its first-long-range missile defence system. Ankara said China had not met all requirements of the $3.4 billion deal.

"The most suitable bid came from China but certain developments led to delays. We will revisit these matters during this trip. If we receive a proposal that enriches the bid, we will view this positively," Erdogan told a news conference in Ankara before departing for China.

Ankara has given mixed messages on whether it will integrate the system with NATO infrastructure or not.

U.S. and European allies want Turkey to use a system that is compatible with NATO's air defence and because they are worried about inherent security risks from Chinese technology.

In Beijing, talks between Erdogan and his Chinese counterpart will focus on bilateral trade, which is now worth about $24 billion, according to official figures.

"The visit's most important topic will be the negotiations between China and Turkey on defence systems," a Turkish official said on condition of anonymity. He added that no final agreement would be reached during the trip.

TECHNOLOGY TRANSFER

During the tender, U.S. firm Raytheon put in an offer with its Patriot missile defence system. Franco-Italian group Eurosam, owned by the multinational European missile maker MBDA and France's Thales, came second in the tender.

Russia was eliminated in the first stage of the tender but the official said Moscow was still keen on providing a surface-to-air missile system - a prospect that would also cause disquiet in NATO.

An official from Turkey's Defence Industry Undersecretariat, which has run the technical negotiations with China, said a major stumbling block has been China's reluctance to make a technology transfer which could give Turkey the knowledge to operate the system and eventually replicate it.

"If this issue is solved, the project will be approved," the official said on condition of anonymity.

But Erdogan may also field complaints about recent protests, some violent, against China's embassy and citizens in Turkey by nationalist Turks angered by China's treatment of Uighurs.

Uighurs, who number about 10 million and live predominantly in the western province of Xinjiang, have had their religious and cultural rights curbed by the Chinese government over concerns about separatism, according to Human Rights Watch. Some Turks believe they share ethnic ties with the Uighurs.

Turkey harbours a sizeable community of Uighur dissidents, and violent protests broke out earlier this month when Thailand forcibly deported nearly 100 Uighurs back to China. The Thai consulate in Istanbul was stormed and reports of attacks on Chinese restaurants and east Asian tourists emerged.

(Additional reporting by Orhan Coskun, Ece Toksabay and Humeyra Pamuk; Writing by Nick Tattersall and Ayla Jean Yackley; Editing by Mark Heinrich)