Michael Gove has announced he will seek the Tory leadership after concluding Boris Johnson 'cannot provide the leadership or build the team for the task ahead'.

In a bombshell announcement that rocked Westminster hours before the close of nominations, the pro-Brexit campaigner who had been expected to back the ex-London mayor threw his hat in the ring.

'I have repeatedly said that I do not want to be prime minister. That has always been my view. But events since last Thursday have weighed heavily with me,' he said.

The declaration is a devastating blow for Mr Johnson, who was expected to stand with the backing of the Justice Secretary.

During the EU referendum campaign, the two men worked side by side to secure the shock Brexit victory and were believed to have grown close.

But an email on Wednesday from Mr Gove's wife that was accidentally sent to the wrong person revealed behind the scenes concerns about the former mayor's leadership bid.

Daily Mail columnist Sarah Vine said in the email that her husband must secure a specific guarantee about his future before making any deal with Mr Johnson and should 'not concede any ground'.

Paul Dacre, editor of the Daily Mail, and media mogul Rupert Murdoch 'instinctively dislike' Mr Johnson, she wrote.

Meanwhile, Andrea Leadsom has announced she is also vying for the party's top job, tweeting: 'Let's make the most of the Brexit opportunities!'

Mr Johnson is set to launch his leadership bid with a speech presenting what was described as a 'positive, optimistic vision' of Britain outside the EU, offering 'a chance to believe in ourselves'.

Home Secretary Theresa May is promising to reunite both the Conservative Party and the country in her bid.

A YouGov poll for The Times of 1,000 Conservative Party members put Mrs May ahead on 36% with Mr Johnson on 27%.

Former defence secretary Liam Fox and the self-styled 'underdog', Work and Pensions Secretary Stephen Crabb, are also putting themselves forward.

The timetable for the contest - which will end with a new prime minister being named on September 9 - was formally approved by the backbench 1922 Committee.

A series of run-offs will begin on Tuesday as MPs whittle down the hopefuls to two, who will tussle for the support of grassroots members in a one-member-one-vote contest.

Michael Gove statement in full

'The British people voted for change last Thursday. They sent us a clear instruction that they want Britain to leave the European Union and end the supremacy of EU law. They told us to restore democratic control of immigration policy and to spend their money on national priorities such as health, education and science instead of giving it to Brussels. They rejected politics as usual and government as usual. They want and need a new approach to running this country.

'There are huge challenges ahead for this country but also huge opportunities. We can make this country stronger and fairer. We have a unique chance to heal divisions, give everyone a stake in the future and set an example as the most creative, innovative and progressive country in the world.

'If we are to make the most of the opportunities ahead we need a bold break with the past.

'I have repeatedly said that I do not want to be Prime Minister. That has always been my view. But events since last Thursday have weighed heavily with me.

'I respect and admire all the candidates running for the leadership. In particular, I wanted to help build a team behind Boris Johnson so that a politician who argued for leaving the European Union could lead us to a better future.

'But I have come, reluctantly, to the conclusion that Boris cannot provide the leadership or build the team for the task ahead.

'I have, therefore, decided to put my name forward for the leadership. I want there to be an open and positive debate about the path the country will now take. Whatever the verdict of that debate I will respect it. In the next few days I will lay out my plan for the United Kingdom which I hope can provide unity and change.'