Jeremy Corbyn has called on the UK's most senior civil servant to intervene to stop Boris Johnson forcing a no-deal Brexit in the middle of an election campaign, amid rising signs the country is heading for the polls again this autumn.

The Labour leader wrote to Sir Mark Sedwill, the cabinet secretary, accusing the prime minister of plotting an "unprecedented, unconstitutional and anti-democratic abuse of power", after it emerged No 10 would be prepared to delay an election until immediately after 31 October if Johnson loses a no confidence vote among MPs.

In his letter, Corbyn demanded urgent clarification of the rules around purdah, which are meant to prevent the government taking major policy decisions during an election campaign.

He asked Sedwill to confirm that if the UK is due to leave the EU without a deal during an election campaign, then the government must seek an extension to article 50 and allow an incoming administration to take a decision about Brexit on the basis of the result.

Lexical item:

purdah (countable and uncountable, plural purdahs)

    (chiefly South Asia) A curtain, especially as used to conceal and divide women from men and strangers in some Hindu or Muslim traditions. [from 17th c.] quotations ▼
    (rare, obsolete) A striped cotton cloth which is used to make curtains. [19th c.]
    The state or system of social gender seclusion in some Muslim or Hindu communities. [from 19th c.]
    A long veil, or other all-enveloping clothing, worn by women in some Muslim societies. [from 20th c.]
    (figuratively) Secrecy, isolation. [from 20th c.]
    (Britain) The period immediately before an election or referendum during which restrictions are in force on the activity of civil servants.