Former UK Chancellor Sajid Javid delivers a withering broadside against prime minister Boris Johnson in his resignation speech.

Javid launched a barely-veiled attack on the "Cummings and goings" of Johnson's senior advisers.

He said Johnson's centralisation of power in Downing Street was "not in the national interest" and warned that the government risked failing to balance the books now he has quit.

Javid resigned earlier this month after refusing to accept Johnson's demand that he sacked his advisers.

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Boris Johnson has suffered the first significant challenge to his leadership after his former chancellor delivered a withering resignation speech in which he accused the prime minister of monopolising power inside Downing Street.

Sajid Javid on Wednesday told the House of Commons that the prime minister's attempts to sack the chancellor's advisers and centralise power in 10 Downing Street were "not in the national interest."

"It has always been the case that advisers advise, ministers decide, and ministers decide on their advisers," Javid said, adding that "no particular person or government has a monopoly on the best ideas."

Javid quit as chancellor earlier this month in a shock move which overshadowed Johnson's Cabinet reshuffle. The prime minister had asked Javid to stay on as chancellor on the condition that he sacked all of his advisers.

In his first parliamentary speech since his resignation, Javid warned that moves by Johnson's senior aide Dominic Cumming to sack ministers and ministerial advisers deemed insufficiently loyal to the prime minister meant that the government risked losing people who are able to "speak truth to power."

"I had hoped to have a little longer to make a difference from the inside."

Watch Sajid Javid's resignation speech

He also suggested his departure came amid pressures to ditch the UK government's spending rules.

"Not everyone at the centre of government always feels the pressure to balance the books," he told MPs.

"Trade offs have to be made somewhere.

"It would not be right to pass the bill for our daily consumption to our grandchildren."

However, he insisted that the prime minister retained his full support as a backbench member of the Conservative party.

Johnson responded by praising Javid's contribution to public life and insisted that he still has many "admirers" in government.