* U.S. ready to offer Iran rapid relief from sanctions
* Washington lawmakers close in on debt deal
* UK's Grangemouth refinery halts work ahead of strike (Updates previous SINGAPORE)
By Peg Mackey
LONDON, Oct 15 (Reuters) - Brent crude slid below $111 per barrel on Tuesday after Iran presented a proposal over its nuclear programme at talks in Geneva, although the prospect of a U.S. debt deal in Washington provided some support.
A spokesman for EU foreign policy chief Catherine Ashton said Iran had made the proposal but he gave no details.
Any deal would be complex and take time, both countries said ahead of the two-day meeting that began early Tuesday.
On Monday the United States held out the prospect of quick relief from sanctions for Iran if Tehran moved swiftly to allay concerns about its programme.
Brent was trading 54 cents lower at $110.50 a barrel at 0956 GMT, after settling down in the two previous sessions.
U.S. oil was down 58 cents at $101.83 a barrel, after closing 39 cents higher.
"We think it would be wrong to dismiss any of this as more of the same-old, same-old," said Credit Suisse in a research note. "That said, we don't anticipate any sudden and meaningful increase in Iran's oil exports in the next few months, or even quarters."
A month-long battle over U.S. government spending may be edging closer to a compromise that would reopen federal agencies and push back the possibility of a default for several months, although hurdles remained as a Thursday deadline drew near.
The talks on Iran's nuclear programme will be the first since the election of President Hassan Rouhani, who has tried to improve ties with the West to pave the way for an end to sanctions, which have cut Iranian oil exports by more than 1 million barrels per day.
Oil prices could fall around $10 per barrel in the event of Iran resuming full exports, analysts reckon.
South Korea more than doubled its Iranian crude imports to 140,000 barrels a day in September from August, customs data showed on Tuesday. Still, volumes remain close to those required by the target of cutting shipments for the June-November period by 15 percent to extend a U.S. sanctions waiver for another six months.
GRANGEMOUTH, U.S. OIL STOCKS
Elsewhere, Britain's Grangemouth refinery began halting work on Monday ahead of a 48-hour strike. In 2008 a strike there interrupted flows of crude through the Forties Pipeline System and shut in production at 70 North Sea fields, pushing up Brent oil prices.
Investors will do without U.S. oil inventory data this week for the first time since 1979, as the Energy Information Administration will not publish its weekly report scheduled for Wednesday due to a lack of government funding.
U.S. commercial crude oil inventories were forecast to have increased 2.3 million barrels in the week to Oct. 11, a Reuters poll of analysts showed on Monday.
Industry group American Petroleum Institute will release its weekly inventory report on Wednesday. (Additional reporting by Jacob Gronholt-Pedersen in Singapore; editing by Keiron Henderson)
