Britain's FTSE 100 <.FTSE> ended the session up 0.3 percent at 7,275.25 points after a volatile start to trading as investors hesitated ahead of the Fed's two-day meeting starting later in the day. European bourses were broadly flat.

The FTSE was boosted on Monday by Bank of England governor Mark Carney saying interest rates were likely to rise in the coming months.

"In our view the driving variable into the end of the year is likely to be the direction of bond yields," said equity strategists at JP Morgan.

They cut UK equities to underweight on Monday, highlighting a strong inverse correlation between the relative performance of the UK and the direction of bond yields.

Financials, which benefit when interest rates are raised, supported the index, with HSBC (>> HSBC Holdings) and Lloyds (>> Lloyds Banking Group) both up around 1 percent, but gains were muted overall.

Energy stocks added the most points to the index as oil prices held close to five-month highs.

Supermarkets Sainsbury's (>> J Sainsbury), Morrisons (>> Wm Morrison Supermarkets), Tesco (>> Tesco) and Marks & Spencer (>> Marks & Spencer Group), whose bricks-and-mortar business models have been squeezed by online delivery services like Ocado, were among top FTSE 100 gainers.

Sales data from Kantar showed inflation helped boost sales growth for the top supermarkets, with Tesco (>> Tesco) coming out on top although its market share was squeezed.

Online grocer Ocado (>> Ocado Group PLC) tumbled 2 percent, however, after its third-quarter results revealed rising short-term costs due to a ramp-up in capacity at its Andover distribution centre and investment in a new centre in Erith near London.

"Management have guided down full-year EBITDA expectations," said Bernstein retail analyst Bruno Monteyne. "This is in line with our view that the market under-estimates the margin impact of setting up the new facilities."

Construction and plumbing supplies distributor Ferguson (>> Ferguson Plc) rose 2.3 percent after Citi upgraded the stock to a "buy" and Barclays reiterated its optimism on it.

Citi analysts said the shares were good value after recent weak performance, and flagged full-year results on Oct. 3 as a "key catalyst".

Barclays analysts said Ferguson could resist pressure on its business model from online alternatives.

"We see Ferguson as being able to match or beat Amazon on the range and availability of products expected by its professional plumber customer base as well as on delivery/collection options," they said in a note.

(Reporting by Helen Reid and Kit Rees; editing by Mark Heinrich)

By Helen Reid and Kit Rees