PRECIOUS-Gold tumbles as Ukraine tensions ease; Fed in focus

* Putin says pulling troops back from Ukrainian border

* White House says no sign of Russian troop pull-back

* Gold market digesting Yellen comments

* Profit-taking seen after gold's recent rally -traders

(Adds comment, second byline, dateline, updates market activities)

NEW YORK/LONDON, May 7 (Reuters) - Gold prices fell about 1.5 percent on Wednesday as investors took profits from a run-up spurred by geopolitical concerns after Russian President Vladimir Putin urged Ukrainian separatists to postpone a referendum and said he was pulling troops back from their common border.

Putin called on pro-Moscow separatists in Ukraine to postpone a vote on secession just five days before it was to be held, potentially pulling Ukraine back from the brink of dismemberment. He also announced he was pulling Russian troops back from the Ukrainian border.

However, the White House said it has seen no evidence that Putin has pulled Russian troops back from the Ukrainian border, and said it wants a referendum on secession to be cancelled, not merely postponed.

The dollar turned higher after Federal Reserve Chair Janet Yellen said in congressional testimony the U.S. economy was still needed lots of support given the "considerable slack" in the labor market even as she said "a high degree of monetary accommodation remains warranted."

"There are still some questions out there about the Ukraine situation, and whether the Fed will increase interest rates or leave them here, so all of these uncertainties are weighing down on gold," said Thomas Capalbo, precious metals trader at brokerage Newedge.

Spot gold was down 1.4 percent at $1,288.73 an ounce by 12:43 p.m. EDT (1643 GMT), on track for its biggest one-day drop in three weeks.

U.S. COMEX gold futures for June delivery fell by $19.50 an ounce to $1,289.10, with trading volume on track to sharply exceed its 30-day average, preliminary Reuters data showed.

In the past three days, gold has risen as much as 3.5 percent to a high of $1,314.70 earlier Wednesday as fears that a stand-off between pro-Russian separatists and government troops in Ukraine could bring the country to war.

The metal also came under pressure after Yellen's comments affirmed a view that the Fed will end its asset purchases this fall as expected.

A week ago, the Fed reduced its monthly bond purchases to $45 billion from $55 billion, keeping the stimulus program on track to be fully wound down by year end. But it also stuck to its assessment that the economy would need near-zero interest rates for a "considerable time" after the asset purchases end, a message Yellen stuck with in her testimony.

Among other precious metals, silver tracked gold's weakness, falling 1 percent to $19.33 an ounce. Platinum fell 1.4 percent at $1,431.24 an ounce and palladium was down 2.3 percent to $795.25 an ounce.

Earlier this week the platinum group metals had been underpinned by a miners' strike at major producers Anglo American Platinum, Impala Platinum and Lonmin , which began on Jan. 23 and has affected 40 percent of global output.

(Additional reporting by A. Ananthalakshmi in Singapore; Editing by Susan Thomas, Dale Hudson and James Dalgleish)