By Jason Lange

WASHINGTON, Nov 4 (Reuters) - Lael Brainard, a top economic diplomat at the U.S. Treasury, will step down from her post on Friday, a Treasury official said, amid reports she is under consideration for a seat on the Federal Reserve Board.

As undersecretary of the Treasury for international affairs since 2010, Brainard has played a key role in pushing China toward a flexible currency and pressing Europe to tackle its debt crisis more aggressively.

The Washington Post and the Wall Street Journal have reported that Brainard is under consideration to fill a vacancy at the Fed. The Treasury official, who spoke on Monday on condition of anonymity, did not disclose the reason for the departure and a White House spokeswoman declined to comment.

Brainard cut her policymaking teeth during the Clinton administration, working alongside many officials who later ended up serving under President Barack Obama, including top White House economic adviser Gene Sperling and Treasury Secretary Jack Lew.

Brainard, who has a doctorate in economics from Harvard University, served as deputy director of Clinton's National Economic Council, where she focused on international trade and financial policy. She was also the U.S. representative to the meetings of the Group of Eight industrialized nations.

The Senate took more than a year to confirm Brainard for her current post, slowed by a committee probe into her personal taxes.

In recent months, she has been seen as a steady hand on international economics for Lew, who became the top Treasury official in February and who had focused mainly on budget issues during his long career in government.

Obama is likely to need to fill several seats on the Fed's seven-person board in the coming months. Fed Governor Elizabeth Duke stepped down in August; Fed Chairman Ben Bernanke is expected to give up his board seat when his term as chairman expires at the end of January; and Obama has nominated Fed Governor Sarah Raskin for a top Treasury post.

In addition, Fed Governor Jerome Powell's term expires in January, although Obama is expected to renominate him.

INTERNATIONAL EXPERIENCE

If nominated to the Fed, Brainard, 51, would bring a familiarity with top economic officials around the globe.

She accompanied Lew on his first two foreign trips, to Beijing and to Europe, and represented him at several international gatherings, including the Group of 20 meetings in St. Petersburg in September.

Before joining the Obama administration, Brainard worked as a senior fellow at the Brookings Institution, where she helped found the think-tank's global economy and development program.