Labour yesterday opened up a confrontation with likely coalition partners over its plans to give police powers to issue "instant Asbos" and impose curfews without having to go through courts.

The proposal for an extension of antisocial behaviour orders was spelled out as the major parties focused on crime policy, and Tories linked the Scottish Executive parties with 13 serious crimes committed by prisoners released early from jail.

The Labour plan to give police extra powers to act without going through a judicial process risks clashes with the two parties most likely to form a coalition with it.

While Greens called for an end to "demonising" young people, the LibDem justice spokesman, Jeremy Purvis, condemned the Labour plan.

Known as community protection orders, Labour leader Jack McConnell compared them with parking tickets issued by traffic wardens, letting police create "instant exclusion zones and curfews". They are aimed at moving persistent offenders away from off-licences and troublespots, and would remain in place until a court was convinced that the individual's behaviour had changed.

The Labour leader said: "I believe there is a need for an instant order, an order the police can deal with there and then which ensures the ring-leaders of some of the disorder, the drunken behaviour we see in our streets, can be put under control right away."

The Labour manifesto is also proposing community courts where the public can have a say in how offenders should pay for their crimes, community police teams with a named officer the public can contact, and a doubling in the number of community wardens.

During a visit to Sauchie and Alloa, Mr McConnell said recent legislation had introduced measures which were "starting to have an effect and bring relief to families, where these are being used properly". But he wanted to go further, with more police powers.

Mr Purvis, however, said the Labour plan for instant Asbos was "illiberal and ill thought out".

He said: "There is already a process for the police to act straight away, and it's called an arrest. If there are to be measures to challenge the behaviour of individuals, that is a role of the judicial system to which police have to present the evidence. Blurring the lines between the police preventing crime and being judge and jury on the streets is not consistent with the Scottish approach, and it won't be effective either."

Tories sought to take the toughest line on sentencing, with leader Annabel Goldie criticising the executive for being too soft in its recent Sentencing Bill. She rejected a call by Tony Cameron, recently retired as director of the Scottish Prison Service, that there should be more community sentences, a reduction in short sentences without rehabilitation, and that jailing more people was not the way to make society safer.

Miss Goldie responded: "If that is the case then what we need to do is change our prison policy, not empty the prisons." She said it was wrong to give offenders more than 10% remission for good behaviour, and argued those facing their third sentence should get extra time added.

LibDems want to sound tough on crime as well, promising sentences of up to seven years for knife crime. Scottish leader Nicol Stephen also repeated plans to recruit 1000 local community police officers.

"Across Scotland, people tell me they want more action to cut crime and make their communities safer," he said. "I want to see more action to deal with local criminals and tackle nuisance behaviour in our communities."

The Greens' justice spokesman, Patrick Harvie, countered: "We predicted authoritarian responses to crime and justice would fail and they have." He called for more resources for the Children's Hearing system and more use of victim-offender mediation.