* Centrica buying 20 pct stake in EDF unit British Energy
* Means EDF gets "Made in Britain" stamp for nuclear plans (Adds details)
LONDON, Aug 7 (Reuters) - Britain's consumer affairs watchdog has approved Centrica's buy of a 20 percent stake in British Energy, helping give the French-owned nuclear firm a "Made in Britain" stamp for its expansion plans.
British Energy owner EDF and Centrica plan to form an 80/20 joint venture to build four new nuclear power stations in Britain, and the approval clears the way for EDF to get the British involvement seen as key to the scheme.
The Office of Fair Trading said on Friday it did not believe the acquisition would decrease liquidity in the wholesale electricity market, a fear that had been raised by companies in the energy industry.
It also said it did not believe the deal would increase the two companies' incentives to co-ordinate within the energy supply and generation market.
In May, the companies announced that British Gas owner Centrica planned to buy the stake for 2.3 billion pounds ($3.86 billion).
They are now waiting for the European Commission to clear EDF's plan to buy Centrica's stake in the Belgian utility SPE, which is also seen as an integral part of the overall deal.
At 1449 GMT, shares in EDF were up 0.8 percent to 34.3 euros, while Centrica shares were up 0.9 percent to 219.5 pence. ($1=.5966 Pound) (Reporting by Ben Deighton; editing by Simon Jessop)