The chairman of a panel examining the pay and expenses of assembly members in Wales has questioned whether some are value for money.
Sir Roger Jones said AMs prioritise constituency work, sometimes at the expense of law-making.
He was speaking on BBC Wales Dragon's Eye programme ahead of the panel's first public meeting in Llandudno.
Sir Roger suggested some AMs could be more effective in other work including scrutinising the assembly government.
He was asked whether AMs did work that was value for money.
"Some do, some more than others," he said.
"The work of the panel is to try and ensure value for money for the people of Wales and if we don't achieve that we have achieved nothing."
Sir Roger, who is also pro-chancellor of Swansea University, said AMs had four functions: establishing institutions, scrutinising the work of Government, law-making and constituency work.
"Now they probably do a reasonable job on constituency matters but the value lies in doing those other things, and I'm not sure we are getting that with the priority we need," he said.
REVIEW GROUP PANEL
Sir Roger Jones, Swansea University pro-chancellor, pictured
Dafydd Wigley, former Plaid Cymru leader
Nigel Rudd, former chief executive, East Midlands Regional Assembly
Jackie Nickson, HR manager, Opagus Group
Another public meeting is due to take place in south Wales in January.
The panel was set up after a controversial 8.3% pay rise for AMs earlier in the year.
It has been gathering the views of the public about levels of pay and expenses.
One of the allowances likely to be examined entitles AMs from outside Cardiff to claim up to £13,000 a year towards rent, mortgage interest and furniture for second homes.
Campaigners have called for the system to be "100% transparent" and for all claims and receipts to be published.
The panel was appointed by the cross-party Assembly Commission after a recommendation by the independent pay review body.
The near-£4,000 increase brought the salary of a backbench AM to more than £50,000 a year.
Currently, members may claim an allowance of up to £15,000 to run their office.
Another allowance, up to £13,000, is available to help AMs who live away from the Cardiff area to stay overnight or find a second home in the capital.
Mark Wallace, campaign director for the Taxpayers' Alliance said when the panel was created, the best way to restore public faith in the system was to publish all expenses claims and receipts.
"From our point of view, taxpayers are under a lot of pressure at the moment given the record tax take and the current economic conditions," he said.
The members of the review group include Dafydd Wigley, the former Plaid Cymru leader, and representatives from business and the public sector outside Wales.
The group is expected to report back before the end of next March to the Assembly Commission, the body responsible for providing property, staff and services to AMs.