British Prime Minister Theresa May is to visit Queen Elizabeth II on Wednesday to gain formal approval for Parliament's dissolution.

Although lawmakers left Westminster last week, their seats were officially left vacant at one minute past midnight on May 3.

Formal negotiations for Britain to leave the European Union are expected to start after a new parliament is elected in the June vote. Prime Minister May called the elections last month in a bid to strengthen her political position in the lead-up to Brexit talks.

Later on Wednesday, the EU's chief negotiator, Michel Barnier, is due to unveil recommendations for the upcoming negotiations with Britain. Barnier has previously indicated that he needs to wrap up talks by October 2018 to get any Brexit deal approved by the EU Parliament in time for Britain's scheduled departure from the bloc on March 29, 2019.

British voters backed Brexit in a closely fought referendum in June last year.