An attack on Iran would be unacceptable, Russian Prime Minister Vladimir Putin said today,but also urged Tehran to show restraint in its controversial nuclear programme. This would be very dangerous,unacceptable,this would lead to an explosion of terrorism,increase the influence of extremists and I doubt very much that such strikes would achieve their stated goal, Putin said. The Iranians should show restraint in their nuclear programme, he added,speaking at a meeting with foreign Russia experts at his residence outside Moscow. The United States and Israel have never ruled out the option of carrying out air strikes to prevent Iran from acquiring an atomic bomb. Tehran denies that its nuclear programme is aimed at building weapons and says it is civilian in nature. (AFP) DEP 09111931 DELHI FLU-WHO School closure most effective at start of flu outbreak: WHO Geneva,Sept 11 (AFP) The World Health Organisation said today that studies indicate that school closures show the greatest benefits against the spread of the swine flu virus when implemented early in the outbreak. The timing of school closure is critically important, said the UN health agency in a note detailing measures that can be taken in schools to reduce the impact of the A(H1N1) pandemic. Modelling studies suggest that school closure has its greatest benefits when schools are closed very early in an outbreak,ideally before one per cent of the population falls ill, it added.