Syringes are handed out to cut the risk of infection

They said some exchanges are making "no attempt or effort" to prevent dirty needles being dumped in public places.

Figures show that at least one in 10 dirty needles carry the hepatitis virus.

The Police Superintendents Association said the numbers of discarded needles has become a "menace" in some areas.

Sharing needles

Every year more than 28 million hypodermic needles are given to drug addicts in the UK.

The aim is to prevent injecting drug users from sharing needles and exposing themselves to Hepatitis and the HIV virus.

Tests on discarded needles found that 10% carried hepatitis strains B and C.

Some needle exchanges where addicts can obtain fresh equipment manage a return rate for old needles of around 70%.

However the senior officers, in day to day operational charge of policing, are highly critical of certain exchanges.

The superintendents said the number of needles discarded in public areas is unacceptable.

They want the exchanges to do more to ensure potentially contaminated needles are returned for safe disposal.

Community protests

The police attack on exchanges follows a decision to reduce the number of clean needles available to drug addicts in Conwy.

Last year 767,000 needles were given to drug users in the north Wales town, drawing community protests over fears more addicts would be attracted to the area.

The local health authority said pharmacists' decision to boycott the scheme could lead to widespread infection if one person with HIV came to an area with no exchange.

And in July residents of a former pit town called for action to drive out drug users after 3,000 used syringes were found in a disused building.