The Liberal Democrats have claimed that a ministerial bid to block junk mail has flopped.

Environment spokesman Norman Baker said on Thursday that the volume of unwanted leaflets has increased in the past year despite promises to cut it.

The party pointed to figures showing a 3.8 per cent rise in the first three months of this year compared with the first quarter of 2003.

And since the government agreed with the the direct marketing industry last year to target mailshots more carefully, the level of junk mail has gone up by eight per cent.

Baker said the Department for the Environment, Food and Rural Affairs (Defra) was ahead of only its German counterpart in tackling the problem.

"Once again, Britain is being left behind by its European partners on reducing unwanted mail," he said.

"Last year's voluntary agreement between Defra and the Direct Marketing Association is simply not enough, and the latest figures show that it is already failing.

"The government accepts that the 'four R's' approach to waste reduction: Reduce, Reuse, Recycle, Recover, is the most effective, but has failed to explore the first two steps.

He added that Defra should promote rather than simply support preference systems.

"The direct mail problem needs direct action. The government should introduce a scheme, similar to that in France, where companies pledge not to deliver junk mail to households displaying a sticker on their door and face fines if they do so," he said.

"Defra should also actively promote the Mailing Preference Service, which blocks junk mail leading to an automatic reduction in waste.

"The constant bombarding of homes with offers and promotions resulted in 5.9 billion pieces of paper through letterboxes in the last year alone. People have a right to say no to unwanted mail, and for that right to be upheld by law."