Former BP Boss Browne is DEA Chairman

Lord John Browne heads DEA's supervisory board

* LetterOne co-owners Fridman, Khan also join

* Unit changes name to DEA Deutsche Erdoel AG

FRANKFURT, March 3 (Reuters) - DEA, the oil and gas company that German utility RWE sold to Russian billionaire Mikhail Fridman, has appointed former BP boss John Browne as its new supervisory board chairman.

Fridman's investment vehicle LetterOne bought the firm from RWE in a 5.1 billion euro ($5.7 billion) deal finalised on Monday, brushing aside British opposition against the sale of some licences held by DEA in the North Sea.

The transaction was first announced a year ago, coinciding with Western sanctions imposed on Russia over the Ukraine crisis, sparking concern in some EU countries about whether a European oil and gas business should fall into Russian hands.

Britain said at the weekend that the deal's structure did not alleviate concerns that any possible future sanctions against LetterOne's owners, which include Fridman and German Khan, could negatively affect production.

Browne, who served as chief executive of BP from 1995 to 2007, was hired this week by LetterOne to head its energy division.

"In DEA, we have acquired a company with long history of technical and managerial excellence, a track record of imaginative thinking, an international outlook, and great potential," Browne said in a statement.

"DEA fits perfectly into our investment strategy."

DEA said that Fridman and fellow billionaire Khan had also joined DEA's supervisory board, adding the group would change its name from RWE Dea AG to DEA Deutsche Erdoel AG, the name it had carried between 1911-1970.

Employing 1,440 staff, DEA is active in 17 countries and holds around 160 exploration and production licences as an operator and as a partner.

It said it was preparing a review of its corporate strategy, but did not provide further details.

($1 = 0.8958 euros)

(Reporting by Christoph Steitz