* EU agrees to ban Iranian crude imports; Geithner China bound
* Nigerian trade unions call for strikes
* Coming up: Weekly U.S. EIA crude inventories at 1600 GMT (Recasts, adds quotes, updates prices, previous SINGAPORE)
By Claire Milhench
LONDON, Jan 5 (Reuters) - Oil edged lower to around $113.40 a barrel on Thursday as a stronger dollar offset fears of supply disruptions to Iranian crude should a European Union agreement to cut off oil imports from the No. 2 OPEC producer come into force.
Brent crude futures were off 37 cents to $113.33 at 1018 GMT, giving up earlier gains as the dollar strengthened.
U.S. crude was down 72 cents at $102.50 a barrel, after reaching an intraday high of $103.73 earlier in the session.
Analysts and traders said oil prices had come under pressure as the dollar strengthened, up 0.59 percent against a basket of currencies at 1018 GMT.
But they added that the risk remained to the upside given geopolitical tensions around Iran and Syria, and calls for strikes in Africa's biggest producer Nigeria which may affect crude oil exports. This is keeping a floor under prices.
On Wednesday, European Union governments reached a preliminary agreement to ban imports of Iranian crude to the EU, although they have yet to decide when the embargo will be put in place.
U.S. Treasury Secretary Timothy Geithner will travel to China and Japan next week to discuss U.S. sanctions on Iran with top government officials.
"It is the geopolitical situation that is supporting the prices, with the possible EU import ban on Iranian oil," said Eugen Weinberg, an analyst at Commerzbank in Frankfurt. "Oil prices are also establishing themselves above $100 in the case of WTI and above $110 in the case of Brent."
Analysts also pointed to potential problems in Nigeria following the government's decision to remove gasoline subsidies at the start of 2012 which has triggered protests and calls for strikes by trade unions.
"Nigeria has a history of long strikes and that can have an impact on overall crude exports - that is definitely something that needs to be watched," said Olivier Jakob, oil analyst at Petromatrix.
He warned that the price of gasoline in Europe per tonne was already above the peak levels seen in the Libyan crisis.
"The West is playing a very dangerous game with Iran - they are making a lot of assumptions, but if you have something blowing up in Nigeria, the prices could really start to get out of control. It is a difficult time to be short oil I think," he said.
Brent has gained nearly 6 percent over the last two sessions and closed at the highest since Nov. 11 on Wednesday. U.S. crude gained 4.4 percent over the same period and settled at its highest since May 10 on Wednesday.
Despite the EU embargo threat, Iran says it is ready to ship its oil to China and other Asian countries as well as Africa.
"The excess Iranian production will continue to be fed back into Asia," said Jonathan Barratt, chief executive of Barrattsbulletin.com. Buyers could strike a deal to buy the crude at lower prices, he added.
Saudi Arabia had said it is prepared to increase output in case of a sudden supply cut. OPEC oil output rose in December to the highest since October 2008, a Reuters survey found, as members showed little sign of cutting output as Libyan supplies recover.
U.S CRUDE STOCKS
A French bond auction which sought to raise up to 8 billion euros in long-term debt drew solid demand following a recent rise in yields.
U.S. crude stocks fell 4.4 million barrels in the week to Dec. 30, industry group American Petroleum Institute reported late on Wednesday, a sharply larger decline that the 200,000-barrel drawdown forecast in a Reuters poll.
The market is now awaiting the weekly data from the U.S. Energy Information Administration, which will come at 1600 GMT on Thursday. (Additional reporting by Florence Tan in Singapore)
