British military trainers working with security forces in Pakistan have been withdrawn at the request of the Pakistani government. The trainers, believed to number about 20, were working with Pakistan\'s frontier constabulary - a paramilitary force on the front line of the fight against the Taliban and al-Qaeda The Ministry of Defence said it was due to \"security concerns\". But it added that the withdrawal was temporary. A spokeswoman said: \"The UK has been asked to withdraw some of its training support teams on a temporary basis by the Pakistan government in response to security concerns. \"We are providing training support at the invitation of the Pakistan government and welcome their advice on these matters. \"The training teams will continue their own training and will be ready to redeploy at the first possible opportunity.\" The United States has already had to bring home more than 100 military trainers. The BBC\'s Orla Guerin, in Islamabad, said relations between Pakistan and its western allies have been under severe strain since US special forces killed Osama Bin Laden on 2 May. Pakistan is still smarting from the raid, which it views as at attack on its sovereignty, she said. British military trainers have been training and assisting Pakistan\'s Frontier Corps in military operations as part of a three-year programme, which started in 2010.