Britain's nuclear regulator issued an interim design approval for Areva's EPR and Westinghouse's AP1000 nuclear reactors on Wednesday, paving the way for UK plant developers to use them in new power stations.

Generic designs for two nuclear reactors proposed for construction in the UK have been granted interim design acceptance by the independent nuclear safety, security and environment regulators, Britain's Office for Nuclear Regulation said in a statement.

Both companies have additional technicalities to clarify but the regulator said it was satisfied they would resolve remaining issues to gain a full licence, which is needed to start construction and costs applicants around 25 million pounds.

Areva will supply two 1,600-megawatt (MW) EPRs to fellow French company EDF to build Britain's first new nuclear power plant in nearly 20 years at Hinkley Point in Somerset.

Toshiba-owned Westinghouse is banking on a selection of its 1,150 MW reactor by German nuclear group Horizon, which unites rivals E.ON and RWE.

This announcement marks a tremendous milestone on the road towards seeing AP1000 reactors built in the UK, said Westinghouse's Vice President for the UK, Middle East & Egypt, Mike Tynan, adding it follows four and a half years of work to gain approval.

The Horizon group intends to select a reactor design early next year and said Wednesday's interim design acceptance gave the group confidence the technologies are suitable for use in the UK.

The chief executive of EDF Energy, the French utility's UK arm, told Reuters on Tuesday that his plan was to follow through one option of also using the EPR to build a new nuclear plant at Sizewell in Suffolk, but added that three years between the Somerset investment decision and the start of the Sizewell project planning left plenty of time to talk.

U.S.-Japanese joint venture GE Hitachi said in September it had plans to enter a new-generation design for regulatory approval next year.

(Editing by Jason Neely)