* Markets await key G20, OPEC+ meetings
* Continued U.S.-China trade war endangers demand
* Many analysts expect extension of output cut
* Tensions over Iran have boosted prices (Updates prices)
LONDON, June 28 (Reuters) - Brent crude oil held near $67 a barrel on Friday ahead of talks over the trade dispute between the U.S. and Chinese presidents this weekend and on production cuts from OPEC on Monday.
Brent crude futures were up 5 cents at $66.60 a barrel by 1350 GMT. U.S. West Texas Intermediate (WTI) crude futures were down 22 cents at $59.21 a barrel.
Brent was on course for a gain of around 25 percent in the first half of 2019 and WTI for a 30 percent gain.
The leaders of the G20 countries meet on Friday and Saturday in Osaka, Japan, but the most anticipated meeting is between U.S. President Donald Trump and Chinese President Xi Jinping on Saturday.
A trade war between the world's two biggest economies has weighed on prices, fanning fears that slowing economic growth could dent demand for oil.
Trump said on Wednesday a trade deal with Chinese President Xi was possible this weekend but he is prepared to impose U.S. tariffs on most remaining Chinese imports should the two countries disagree.
"The next few days will provide a much-needed dose of clarity for the oil balance over the coming months," PVM's Stephen Brennock said in a note.
"Market bulls will be (hoping) that the G20 summit will provide a trade breakthrough ... All the while, the supply side of the oil coin continues to display bullish signals," he added.
The Organization of Petroleum Exporting Countries and some non-members including Russia, known as OPEC+, will hold meetings on July 1-2 in Vienna to decide whether to extend their supply cuts.
"The market sentiment is that OPEC+ will agree to extend cuts, but after all what matters is how deep the cuts will be and how much Saudi Arabia and Russia will curb," said Kim Kwang-rae, a commodity analyst at Samsung Futures in Seoul.
OPEC+ members agreed to curb oil output by 1.2 million barrels per day from Jan. 1.
Oil prices could stall as a slowing global economy squeezes demand and U.S. crude floods the market, a Reuters poll of analysts found, despite an expected extension by OPEC and its allies of their output-cutting pact.
The survey of 42 economists and analysts forecast Brent crude would average $67.59 a barrel in 2019, down from the $68.84 estimate in May.
Tensions between the United Sates and Iran have also been keeping markets on edge.
A week after U.S. President Donald Trump called off air strikes on Iran at the last minute, the prospect that Tehran could soon violate its nuclear commitments has created additional diplomatic urgency to find a way out of the crisis.
(Reporting by Jane Chung; Editing by Elaine Hardcastle and David Evans)