* Risk appetite picks up a little

* "Remain" leads before UK referendum, bookmakers say

* Yellen hints at no rate hike in July

(Updates with early U.S. market activity, changes dateline, previous LONDON)

By Edward Krudy

NEW YORK, June 22 (Reuters) - Stocks and sterling rose while safe-haven assets gold and bonds slipped on Wednesday, as investors grew more optimistic Britain would vote to remain in the European Union in its referendum on Thursday.

Riskier markets also drew support from Federal Reserve Chair Janet Yellen's comments on the U.S. economy on Tuesday, when she virtually ruled out a July interest rate hike.

Wall Street stocks gained 1 percent so far this week although the mood was cautious, with the potential for new opinion polls to swing markets.

The Dow Jones industrial average rose 20.48 points, or 0.11 percent, to 17,850.21, the S&P 500 gained 5.04 points, or 0.24 percent, to 2,093.94 and the Nasdaq Composite added 19.69 points, or 0.41 percent, to 4,863.46.

The MSCI's all-country world stock indexrose 0.6 percent for a 2.6-percent gain so far this week.

Betting patterns with bookmakers have shown a re-opening of the gap in favor of "Remain" after the murder last week of a pro-EU lawmaker appeared to derail the "Leave" campaign.

Stock market gains were more pronounced in Europe. Europe's FTSEuroFirst index of 300 leading shares was up 0.8 percent , Germany's DAX was up 1.1 percent, France's CAC 40 up 0.9 percent and Britain's FTSE 100 up 1.1 percent.

Sterling rose around 0.4 percent against the dollar, climbing above $1.47 and edging back towards Tuesday's $1.4781. The pound has risen 5 percent since dropping to a three-month low of $1.4010 on Thursday.

"Part of it is gradually more and more the risk from Brexit being removed, something that started last week when we saw the polls changing around," said Charles St-Arnaud, senior strategist and economist at Nomura Securities International in London.

The dollar slipped 0.1 percent against the yen to 104.66 yen, and the euro rose 0.6 percent to $1.1306> . .

Fed chief Janet Yellen said on Tuesday the risk of Brexit was something that needed watching "very carefully", but she added that the central bank's ability to raise interest rates this year may hinge on a rebound in hiring.

Yellen continued her testimony in front of the U.S. House Financial Services Committee on Wednesday, with investors listening for clues about the central bank's thinking on the state of the economy and the timing of interest rate hikes.

Benchmark 10-year U.S. bond yields rose slightly to 1.71 percent. Germany's 10-year yield edged up a basis point to 0.06 percent .

As investors grew more hopeful of a "Remain" vote, spot gold languished, falling 0.2 percent to a near-two-week low of $1,265.60 an ounce.

Brent crude futures fell 0.4 percent to $50.43 per barrel. The new benchmark August contract for U.S. crude futures rose 0.2 percent to $49.77. (Additional reporting by William Schomberg, editing by Larry King and Nick Zieminski) ((edward.krudy@thomsonreuters.com ;)(+1 646 223 6314;)(Reuters Messaging: edward.krudy.reuters.com@reuters.net))