A British think tank plans to take legal action over whether the government can take Britain out of the European Economic Area and leave the single market as part of its exit from the European Union, the BBC reported.
The BBC said the group British Influence believed the government could be acting outside the law if it did not get a clear legal opinion as to whether Britain's membership of the EEA automatically ended along with its membership of the EU.
"We consider that ... they have an obligation to seek urgent clarification in the courts. So we are going to be petitioning for a judicial review," the BBC quoted Jonathan Lis, the deputy director of British Influence, as saying.
British Influence said a legal challenge is likely as it believes leaving the EU does not mean quitting the EEA which extends the single market's tariff-free trade in goods to countries like Norway, Iceland and Liechtenstein.
A spokeswoman for the government said Britain was only party to the EEA Agreement in its capacity as an EU member state.
"Once we leave the European Union we will automatically cease to be a member of the EEA," the spokeswoman said.
"The referendum result will be respected and we intend to invoke Article 50 no later than the end of March next year."