Civil servants will be paid to take time off to attend union conferences under a new deal between Labour and unions - a move described as an 'insult to taxpayers'. 

Under new guidance, the 'hard cap' on the proportion of a department's paybill allocated to union 'activities', including conferences, and 'duties', including pay negotiations, will be removed. 

Union reps will be required to allot half of their time to their contractual work, while they may spend the remainder of their time engaging in trade union work - which previously had to be taken as holiday or unpaid leave. 

The move, funded by taxpayers, is viewed by the UK's largest civil service union as delivering 'radical improvements' on the existing 2018 framework.

The new rules will apply to all Whitehall civil servants and workers for public bodies, including prison officers and immigration workers.

It comes amid the passing of the Employment Rights Bill, which gained Royal Assent last year, which will give additional powers to public sector union reps. 

Martin Cavanagh, the national president of the Public of Commercial Services Union (PCS), said: 'We've worked hard, not only to relieve the time pressures faced by our hard-working activists, but also to make attending our union conferences more accessible - particularly for those reps with caring responsibilities, whose annual leave is particularly precious.'

He added the move will make the framework of the PCS 'even more democratic'. 

Notably statutory duties such as health and safety will be left out of the 'maximum' time limit.

The shift has faced backlash from the Conservatives, with allegations Labour is bowing down to the unions - and their demands. 

Alex Burghart, the shadow cabinet office minister, described it as an 'insult to taxpayers', especially amid the reality faced of a decline in public sector productivity. 

He added: 'The public expect civil servants to be getting on with the job of government and delivering on their priorities - not funding their jollies to union bashes.'

This comes as around £90million of taxpayers' cash was spent by councils, schools, Whitehall departments and the health service last year to cover the cost of staff partaking in trade union work. 

Of more than 20,000 union representatives embedded in public bodies, 14,976 (74 per cent) indulged in paid leave to work on union activities. 

The arrangement, known as 'facility time', gives public sector workers the right to be paid their wages while carrying out trade union activity. This can include handing out leaflets and plotting industrial action. 

Therefore it means tax payers have helped fund strike plots that have crippled their public services, including resident doctors' walkouts, HM Revenue and Customs strikes and industrial action by bin collectors. 

The new watered down rules, first reported by Civil Service World, mean union reps will be able to work on union 'activities' as part of their paid working day - rather than the previous arrangement of paid leave. 

This may include attending conferences, collaborating with other reps and educating themselves further on union work.

The new guidance encourages departments to 'explicitly consider' offering paid time off for union reps to attend their trade union's annual conferences. 

It adds the events are 'a valuable means of fostering constructive industrial relations and enabling the setting of policy'.

The previous 'hard cap' will be removed on the proportion of a department's paybill that can be allocated to facility time, with a previous compulsory limit of 0.1 per cent.  This has now been set as a 'suggested guideline'.

Overall facility time cost Whitehall departments £13.8million last year, up from £10.9million three years ago.

More than 3,600 civil servants enjoyed at least some paid leave to work on union activities, with 1,065 spending over half their time on union business.

The organisation with the largest facility time bill was the Ministry of Justice - £3.2million. This was followed by HM Revenue and Customs (£2.3million) and the NHS Lothian health trust (£2.2million).

The public body with the largest number of union representatives embedded in the organisation was the Department for Work and Pensions - 1,014.

This was followed by HM Revenue and Customs (776) and the Ministry of Justice (647).

A Government spokesperson said: 'Facility time, which gives trade union representatives time to represent members, has been a legal right for decades, and we expect that civil servants' focus remains on their primary roles.'