Public safety will be put at risk and emergency services stretched to breaking point unless the government provides funds over and above its “hollow” new drugs strategy, Andy Burnham has warned.

The mayor of Greater Manchester said he did not believe the Home Office proposals were radical enough to tackle the worsening drug crisis in cities across Britain.

He said the “disappointing” revised strategy would have dire consequences if it was not backed with more funding for the police: “The police are at their limits here at the moment with everything else we have on. There will be consequences for public safety.

“There will be consequences in terms of provision of 999 emergency services. We can’t be expected to do all of these new things without any more funding.”

The 2017 drugs strategy, published on Friday, comes amid a sharp rise in drug-related deaths despite falling levels of use. It targets psychoactive substances (formerly known as legal highs), performance-enhancing drugs including “chemsex” substances, and misuse of prescription medicines.

Speaking at Manchester Metropolitan University at a summit on tackling the formerly legal high known as spice, Burnham said he did not believe the strategy was particularly new, and that many of its proposals were already under way in Greater Manchester.

“What’s disappointing is, where’s the money?” he said. “Our public services were in danger of being overwhelmed earlier this year and in light of recent events that they have been dealing with.

“Where is the extra help for them to put into place some of the principles that have been spoken of?”

He added: “I haven’t seen any mention of new money and it seems quite hollow, what was being said.

“If there’s a recognition that there is a need for a better response, well, it needs backing up with the resources to put it into place and it seems to me that is still missing.”

The drug strategy was published on the morning that experts from academia, police, probation service, prisons, NHS and local government gathered in Manchester for the one-day summit.

A synthetic drug often likened to cannabis, spice is illegal to buy, sell or possess in the UK but it is cheap and readily available from dealers around the country.

Use of the drug has reached crisis point in Britain’s prisons, where it is popular because it is undetectable, and is estimated to be used by as much as 95% of Manchester’s homeless population.

At its height, Greater Manchester police attended 55 spice-related incidents in one evening in April this year, amid rising public concern about its effect and the safety of its “zombie” users.

The drug, which is a Class B substance, has also added to the strain on emergency services in Wrexham, north Wales, and in Newcastle, where ambulance service dealt with 263 calls to spice-related incidents in January 2016.

There is mounting concern among experts about a new strain of spice that left 10 people in hospital in Oldham last month. The new crystal form was found to be 100% pure, 20 times stronger than the strain usually smoked in joints.

Dr Robert Ralphs, a senior lecturer in criminology at Manchester Metropolitan University, said spice had become particularly popular among prisoners and homeless people.

“Where it’s used by those vulnerable groups, the homeless and the prison population, it’s driven by the non-detectability, that it’s affordable and functional,” he said.

“It’s used to block out the trauma of being in prison and being on the streets to make prison time or life on the streets go faster. Whether it’s legal or Class A, B or C, that’s not going to make any difference to the motivations of why people are using it.”

Ralphs welcomed a proposal in the government’s new drug strategy to develop clearer clinical guidance on dealing with spice-related patients. “I think what we’ve heard today is we need more of that because there’s a knowledge gap there and a lapse in service provider knowledge about how to tackle it,” he said.