Downing Street insisted ministers are entitled to be 'robust' today after Steve Barclay became the latest minister to face civil service bullying allegations.

No10 lined up behind the health secretary after Foreign Secretary James Cleverly said his colleague is 'absolutely not' a bully despite claims officials had 'raised concerns' about his behaviour.

The Guardian said civil servants had complained informally to permanent secretary Chris Wormald since Mr Barclay was appointed last summer.

But colleagues have dismissed the 'absurd' allegations, suggesting civil servants now feel 'emboldened' to 'go after' ministers after deputy PM Dominic Raab was forced to quit last week.

Some Tories have lashed out at the 'snivel service' warning that the criticism is in 'snowflake territory'.    

Mr Cleverly told Sky News: 'I've worked with him on a number of occasions.

'He has made a statement making it absolutely clear that there have been no reports.

'His statement is clear and completely unambiguous, and I am completely convinced that that is accurate.'

Sources told The Guardian that Mr Barclay – a former Government whip and Brexit Secretary – was 'constantly angry' and had 'blasted' staff, who in turn found him 'quite challenging'.

One source was quoted saying: 'Barclay's style is very macho... he hauls people over the coals and is a bit unpleasant.'

But a source close to Mr Barclay insisted: 'This is all a bit thin. There's been no complaint at any department he's worked in. 

'The allegation is completely untrue.'

Downing Street denied the PM had ever been told of any informal concerns about the minister's behaviour.

The spokesman said: 'The Health Secretary is delivering for the public and working hard to cut the waiting lists so people can get the care they need more quickly.

'The Prime Minister expects ministers to drive delivery in their department.

'Ministers should be able to test and challenge civil servants and their political advisers robustly, and hold departments to account to deliver for the public.'

One Tory who has worked closely with Mr Barclay told MailOnline the claims were 'absurd'. 'He can be hard work but honestly, it seems absolutely mad.'

Another veteran aide said: 'I'd heard he could be short with people, but we are probably getting into snowflake territory.'

One senior Tory told Politico's Playbook: 'This drivel about Barclay — this is the absolute worst of the snivel service. 

'There are loads of brilliant people in there working extremely hard. But they are being let down by a bunch of activists who are routinely breaking the civil service code to brief and actually lie to the media.' 

A senior civil servant who worked with Mr Barclay in the Cabinet Office said: 'I do not recognise any of these allegations. 

'He was always professional. He set high standards, but he was running a Government department.'

Another said: 'This is open season on ministers.'

Ex-Cabinet minister Jacob Rees-Mogg called Mr Barclay 'effective' and 'tough', adding: 'Dominic Raab's departure emboldened civil servants to go after a government they do not like.'

The Health Department said it had not received formal complaints about ministers' behaviour.