Rhondda's Labour MP Chris Bryant - who says the problem of drug misuse is growing in his constituency - will tackle Mr Blair in a Commons debate on Wednesday morning.

Deprived areas of Wales attract dealers

Mr Bryant wants a new co-ordinator to guide the combined efforts of local government, the Welsh Assembly, and the UK government in tackling the problem.

It comes as the Home Affairs select committee publishes a report calling for significant changes in British drug laws, including the downgrading of ecstasy and extending the availability of heroin on prescription.

According to Mr Bryant, drug addicts face a 12-month wait for rehabilitation, and he claims that could be cut to three months if just one additional nurse was employed.

The MP is expected to recount his visit to police cells in his constituency last Friday night, where he noted that all of those locked up had to be prescribed the heroin substitute methadone.

Drugs like heroin are now rife in south Wales

"The doctors were there as much as the lawyers," he said.

Overdoses

Experts have described heroin-related overdoses in the south Wales Valleys as reaching epidemic proportions.

It has been estimated that, in the Rhondda Cynon Taff area, as many as 12 people a week overdose on the class A drug.

Figures revealed in a BBC Wales documentary last year followed warnings from a judge at Merthyr Crown Court that the valleys were "awash" with heroin.

Campaigners have said more resources are needed to tackle the root of the problem.