Schools Secretary Ed Balls has asked Sir Alan Steer, who has carried out a review of pupil behaviour, to investigate extending existing powers to search for guns and knives.

He unveiled the plans – which teachers will be able to choose whether to use – as teachers threatened to strike in any school where the authorities fail to tackle unruly behaviour.

Parents undermine classroom discipline by demanding that their "little angels" are reinstated after they have been suspended, members of the NASUWT union said at their annual conference, where they passed a motion backing strikes if behaviour problems are not tackled.

Mr Balls, MP for Normanton, also launched a two-pronged attack on teachers who condemned military visits to schools and footballers who are badly behaved, saying it set a bad example.

Speaking after backing proposals for cinema-style age classifications on video games to protect children, Mr Balls said he believed head teachers should be given the powers to search pupils for drugs, alcohol and stolen property if they wish.

The move would extend powers given to schools last year to search pupils for weapons using airport-style detectors.

"I am writing to Sir Alan Steer to ask him to look at whether he agrees with me we should extend the search powers to alcohol, drugs and stolen goods," Mr Balls told journalists at Westminster, saying there was a "very strong case" for the extra searches.

He said schools would not be forced to use the search powers – which were cautiously welcomed by unions – and said a final decision should be taken in the autumn.

Hitting out at bad discipline by some leading Premiership footballers, Mr Balls said: "They are setting a bad example. it's not good for young people to see their heroes on TV behaving in some of the ways some have behaved."

But while Mr Balls was defending the Government's record at dealing with behaviour in schools, at the NASUWT conference in Birmingham delegates warned Ministers must act to reinforce the status of teachers as "authority figures".

The conference passed a motion calling on the union's executive to "authorise disputes in schools, including the use of strike action" where behaviour problems have not been solved.

Susan Jones, a union officer from Derby, said: "At the end of the day if we are unable to secure safe working practices with pupil behaviour managed appropriately, we need to be able to ballot for industrial action."

Delegates also condemned the practice of headteachers "swapping" pupils who have been thrown out under pressure to keep their exclusion figures low.

On Wednesday, a Government report recommended schools share responsibility for problem pupils.

Mr Balls announced that he will change the law "at the earliest opportunity" to require all state school to work in local "behaviour partnerships" to deal with unruly youngsters. He said behaviour issues would only be solved if schools work together.

Responding to the National Union of Teachers' calls for military recruitment in schools to be banned, he said: "In my view many of the comments which were made in the conference and in the press saying there should be less of a role for the military in schools are wrong, misconceived and don't have the support of me and my team."