The police and prison service in Scotland have no record of how many so-called legal highs they have seized, the Tories have claimed.
Conservative MSP Alex Johnstone said Police Scotland must now "urgently" put in place a strategy to detail the amount of new psychoactive substances (NPS) in circulation.
He raised the issue ahead of a debate in Holyrood on the problem.
A motion from community safety minister Paul Wheelhouse highlights the "serious impact that these substances are having in communities, sometimes with fatal consequences".
There were 113 deaths in Scotland in 2013 where such substances were present, compared with 47 in 2012.
Mr Johnstone said: "We know all too well that new psychoactive substances are a threat to our local communities and the health of Scotland's young people.
"Police Scotland is doing its best to battle this issue on the ground but it urgently needs to put a strategy in place to detail exactly how many of these substances are in circulation."
The Conservatives used Freedom of Information legislation to request details of NPS seizures in recent years.
Police Scotland said it was "unable to provide any information" on this, stating: "If an individual is arrested and, upon search, an unknown substance is found, this is recorded in the officer's notebook and sent for field testing to ascertain whether it is an illegal substance.
"It may further be recorded in a retention book (where potential productions/evidence are recorded) at a local station or custody suite.
"These methods of recording are not electronic throughout the country and as such the only way to provide this information in an accurate and consistent manner would be to individually examine each notebook and retention book."
The Scottish Prison Service (SPS) said the information requested was not held by the service as "current SPS drug testing equipment is unable to identify new psychoactive substances".
Mr Johnstone said: "You would think that the single force would have a centralised database listing how many of these drugs have been seized at the point of arrest or even through stop and search.
"Right across Scotland people are getting their hands on these potentially lethal drugs and there's very much a feeling in our communities that we are powerless to do anything about it.
"The Scottish Government has made some good progress so far in tackling the scourge of 'legal highs', but it's clear that it cannot be complacent."
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