LONDON (Reuters) - Britain’s government will propose on Thursday to seek a delay to Brexit until June 30 if parliament approves a deal to leave the European Union by March 20, the parliamentary Speaker said on Wednesday.

Lawmakers are due to vote on a possible extension on Thursday, when the government will also say that if no agreement has been approved by parliament by March 20, it is unlikely that the European Union will approve any extension at its summit on March 21-22 without a specific reason to do so.

If the deal is passed by March 20 “then the government will seek to agree with the European Union a one-off extension ... for a period ending 30 June 2019 for the purpose of passing the necessary EU exit legislation”, the Speaker John Bercow told parliament.