Bishops are claiming up to £27,000 a year in fixed-rate allowances to attend sessions of the House of Lords on top of their travel costs. The Bureau of Investigative Journalism and The Independent has found that some bishops are claiming up to the maximum fixed allowance for attending sessions in the second chamber while having full-time jobs in their dioceses. Others attend sessions in the House without making any claim on the public purse.

Under current regulations peers are given the choice of three daily rates to cover their hotel and living expenses in London – £300, £150 or nothing. However they do not have to provide receipts and can also claim travel expenses.

One bishop, known as a Lord Spiritual, is required to be in attendance and lead prayers on each day the House is sitting. But an analysis of the Lords allowances reveals that some bishops are spending up to two weeks in every month in the Lords – sometimes claiming the maximum allowances.

From October 2010 to November 2011:

* The Bishop of Chester attended the House on 97 days, claiming £27,600 in attendance allowances and £7,309 in travel expenses.

* The Bishop of Liverpool attended on 60 days, claiming £15,600 for attendance and £4,220 in expenses.

* Other significant claimers included the Bishop of Exeter (£11,550), the Bishop of Leicester (£8,850) and the Bishop of Wakefield (£10,650).

In contrast, a number of bishops regularly attended the House but did not claim any attendance allowances at all. The Bishop of Birmingham attended the House of Lords on 22 occasions but claimed no money. The Archbishop of York attended on 16 occasions and claimed nothing. The Archbishop of Canterbury also made no charge. However, the Bishop of London claimed £3,750 for attending the Lords on 24 occasions.

The Church of England has a guaranteed presence in the upper house reflecting its position as the country's established religion. Despite ongoing attempts to reduce their ranks or introduce representatives of other faiths, there are still places in the Lords for the 26 Lords Spiritual. Bishops can choose to attend on an ad hoc basis when matters of interest and concern to them are before it.

Under government plans, the number of bishops allowed to sit in the House of Lords would be reduced to 12 – with the idea of allowing some other faiths guaranteed representation.

Bishops live rent-free in their diocese, and to cover additional costs of running their historic homes they can draw upon allowances covered by the Church Commissioners, who manage the Church's £5 billion property and shares portfolio.

They are provided with official cars for travelling around their diocese, and can claim for entertaining guests, minor repairs to their homes, heating and lighting, gardeners and cleaners.

A spokesman for the Bishop of Chester told The Independent: "The bishop's attendance in the House of Lords was higher than usual for the period in question because of his membership of the Joint Select Committee on Privacy and Injunctions, which required him to attend weekly for several months. And being from the north, he has greater accommodation costs than many other bishops."

The Bishop of Leicester said the amount claimed would vary depending on how much time bishops had to spend in London, whether they could travel home after the session and whether they needed support for their work. He added: "None of this money goes to individual bishops to subsidise their stipends."

In a statement the Bishop of Exeter confirmed: "The Bishop of Exeter claims the allowance for which he is entitled for each day he is in the chamber. As he has to travel up from Devon, the allowance is used to cover overnight accommodation costs, incidental travel costs and subsistence, as well as journals and papers to inform work carried out while in the Lords. Travel to and from London is met by the House of Lords' credit card."

A Church of England spokesman said: "Lords Spiritual, like other members of the House of Lords, are able to claim reimbursement for the costs incurred in the exercise of their parliamentary duties. Claims for reimbursement for costs incurred by the Lords Spiritual under the parliamentary scheme are handled by each individual bishops' diocesan office. The amounts claimed as reimbursement by Lords Spiritual will inevitably vary from bishop to bishop as a reflection of a number of factors including time spent in the House, geographical distance from Westminster, policy portfolios held, committee membership and all party group activity."

Andrew Copson, of the British Humanist Association, said the claims underlined the need for reform. "Church of England bishops acquire their right to sit in our Parliament and claim public money for their expenses solely by virtue of their religion and position in the hierarchy of one denomination of one church," he said.

"Lords reform should end this mediaeval hangover of automatic reserved places for bishops in our legislature."