GPs are being urged to prescribe men who need Viagra just two pills a month, it has emerged.

The South Central Priorities Committee, a panel of NHS managers that makes rationing recommendations for several areas including Buckinghamshire and Oxfordshire, told doctors there should be a twice-monthly limit on erectile dysfunction drugs.

This is despite NHS guidance saying there "appears to be no clinical reason to restrict the number of tablets" of Viagra prescribed to an individual.

It does note, however, that research suggests people have sex four times a month: "The average frequency of sexual intercourse in the 40 to 60 age range is once a week."

In the latest document from the committee, GPs are urged to apply the two-tablet limit to prescriptions for the erectile dysfunction drugs sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis).

The latest document said the committee "has considered the evidence of clinical and cost-effectiveness, and the financial impact on the health economy of treatment for erectile dysfunction" and recommends patients are treated "with a frequency of dosing of two times per month using the drug with the lowest acquisition cost".

The findings were uncovered by Pulse magazine.

Dr Paul Roblin, representing GP medical committees in Berkshire, Buckinghamshire and Oxfordshire, said the guidance was "getting in the way of GPs having a sensible dialogue with patients about their requirements".

"Local priorities committees don't understand the only restrictions on GP prescribing come from the national black list and grey list," he said. "They sometimes portray recommendations as a rule that has to be obeyed, and that's not true."

A spokesperson for NHS Oxfordshire, one of the trusts covered by the policy, told Pulse: "Any decision made by the PCT cannot prohibit prescribing, but will form a recommendation to GPs."