Extra 20 assembly members could cost up to £9m extra a year

Increasing the number of AMs from 60 to 80 would cost up to £9m in the first year, according to a new report.

The Assembly Commission, which runs its day-to-day administration, suggests that moving to 100 AMs would add up to £17m to the current £50m budget.

The commission said it would be "a modest and reasonable price to pay" for effective scrutiny of £15bn of public spending every year.

The Welsh government has said there is "no appetite" for more politicians.

Presiding Officer Rosemary Butler called for an increase to 80 AMs, in response to the additional powers and responsibility being devolved to Wales.

"Assembly Members are thinly spread, especially in their committee work, and these pressures will only intensify as our legislative and fiscal responsibilities increase," she said.