By Tricia Wright

LONDON (Reuters) - FTSE fell on Wednesday with traders saying investors were shifting positions ahead of the conclusion of a U.S. Federal Reserve meeting which could give hints about the longevity of its stimulus programme.

By 0908 British Time, the FTSE 100 was down 37.17 points, or 0.6 percent, at 6,337.04, having risen 0.7 percent in the previous session to end at its highest level in more than a week.

"What you're seeing at the moment is probably just a little bit of position adjustment given the fact that we were at the highs of the week," Michael Hewson, analyst at CMC Markets, said.

Investors' focus will be on Fed Chairman Ben Bernanke's news conference, half an hour after the central bank's post-meeting statement due at 1800 GMT, which could provide clues over whether the Fed might soon begin to scale back the pace of its asset purchase programme.

But since the FTSE 100 has seen a solid run of gains in the run up to the meeting, with Tuesday's advance marking its fourth consecutive day of rises, some investors reckoned that an outcome whereby the Fed said it expected to keep its options open on the pace of bond-buying had already been priced in.

"I think the rally in the last couple of days suggests that investors are anticipating that they get what they want to see... i.e. that (the Fed) remain(s) committed to preserving the support in the medium term (and) decisions will remain data dependent."

"The upside might be a little bit limited after the move that's already happened," said Ian Williams, equity strategist at Peel Hunt.

Stocks trading without the attraction of their latest dividend weighed on the FTSE 100 on Wednesday, with Experian, Land Securities, Severn Trent and United Utilities knocking around 1.8 points off the index.