* Iraqi oil exports unaffected as govt tightens security
* Iran, world powers to meet in Vienna for nuclear talks
* UK to re-open embassy in Iran
* Iraq's main refinery shuts down
LONDON, June 17 (Reuters) - Oil was steady at around $113 per barrel on Tuesday, as signs of a thaw in relations between Iran and the West offset fears that Iraqi exports could be hit by spreading violence in OPEC's second-biggest oil exporter.
Scores of Iraqis were killed on Tuesday during a battle for a provincial capital, and fighting shut the main oil refinery, starving parts of the country of fuel and power as an uprising by Sunni insurgents threatened Iraq's survival as a state.
Islamic militants have seized towns in the north of the country in the past week, although Iraq's 3.3 million barrels per day of oil exports remain unaffected so far.
Brent prices rose around 4 percent last week, the most since July last year, but the rally has paused since the Iraqi government tightened security.
"(The rally) has paused rather than come to an end and it will go substantially higher if there's any threat to the south (where the majority of oil production is centered)," said Christopher Bellew at Jefferies Bache.
"A threat to Baghdad could affect mechanisms for buying and selling oil, too."
BP Chief Executive Bob Dudley said on Tuesday the oil company's operations in Iraq were unaffected by the violence.
Still, Iraq's oil growth targets look increasingly at risk, the International Energy Agency said, highlighting the threat to supplies from political instability and violence.
Underlining that threat, Iraq's biggest oil refinery, Baiji, has been shut down and its foreign staff evacuated, refinery officials said on Tuesday.
Brent crude for August delivery was up 1 cent to $112.95 per barrel by 1327 GMT. The contract settled 48 cents higher on Monday, after touching an intraday high of $113.28.
U.S. July crude was down 30 cents at $106.60 a barrel, after closing 1 cent lower. The U.S. July contract expires on June 20.
Andrey Kryuchenkov, analyst at VTB Capital, calculated a $5 risk premium in the oil price, but added that the outage of Libyan oil exports, which are down to almost nothing from above 1 million barrels per day, were also an important factor.
Britain plans to re-open its embassy in Iran, Foreign Secretary William Hague said, 2-1/2 years after a mob ransacked the embassy.
Hague made the announcement as U.S. and Iranian officials discussed the Iraq crisis, although both ruled out military cooperation.
They met on the sidelines of a meeting which started on Tuesday in Vienna as Iran and six world powers aim to narrow differences and end a decade-old nuclear dispute.
A successful outcome could see additional Iranian crude exported to global markets if sanctions are eased, although no such move is expected imminently.
Threats to supply have emerged elsewhere, however. Russia cut off natural gas supplies to Ukraine on Monday in a dispute over unpaid bills that could increase demand for alternative fuels such as oil.
(Additional reporting by Jacob Gronholt-Pederson in Singapore; editing by Jason Neely and Keiron Henderson)