THE Federal Government will have a "trigger point" next month to increase the age pension, which it yesterday said was inadequate.

Pensions will be increased by a few dollars on September 20 as part of the twice-a-year inflation adjustment, but National Seniors Australia urged the Government to go further and deliver a $30-a-week rise for the single age pension.

The Treasurer, Wayne Swan, said the pension rate was inadequate but the Government would wait until next year before making a "very big structural change in the budget".

The National Seniors chief executive, Michael O'Neill, said pensioners were hurting and if the Government knew the pension rate was inadequate now, it would be much worse by the middle of next year and the most vulnerable could not afford to wait.

Since the budget, the Government has come under pressure to increase the pension. It has responded by announcing the rate and structure would be looked at as part of its tax review. It will receive a report on the pension in February ahead of an expected announcement in next May's budget.

Today's Herald/Nielsen Poll shows in the past four months support for the Government and the Prime Minister, Kevin Rudd, among the over-55 age group has slumped. Mr Rudd's approval rating had dropped from 65 to 51 per cent since May. Among all other age groups, his approval rating remains above 60 per cent.

Labor's primary vote among the over-55s has fallen from 43 to 37 per cent since May. Among other age groups it ranges from 44 to 51 per cent.

Mr O'Neill said the single age pension of $273 a week was not enough to meet the rising cost of living due to higher petrol, transport, food and grocery prices. He said that it would cost about $750 million to pay the nation's estimated 600,000 single age pensioners an extra $30 a week.

"The Government could move quickly on that now as an interim measure," he said.

"There is a really practical opportunity to make a change to the single age pension in September. They should be able to flick the switch for that group. It would send a message beyond words and reviews for those folk doing it tough."