LONDON - British Foreign Secretary David Miliband has said President Asif Ali Zardari and Former Prime Minister Mian Muhammad Nawaz Sharif should forget differences and join hands to meet the internal challenges as Pakistan is facing a 'mortal threat' from its internal enemies amid worsening security in the country. It is now vital that rival democratic forces unite to combat the "very grave" security situation, he told BBC radio in the wake of the attack on the Sri Lanka cricket team. "It's now vital that whatever the political differences between President (Asif Ali) Zardari, Nawaz Sharif, the leader of the opposition... come together to unite against the mortal threat Pakistan faces, which is a threat from its internal enemies, not its traditional external enemies," Miliband said. "This is a very grave situation and it's intimately linked to the situation in Afghanistan. It's getting worse in a number of respects." He added: "The tempo of terrorist attacks has risen and the combination of political uncertainty, economic decline... and then the security side mean that this is a particularly challenging time for any government. "The degree of political disunity that exists at the moment is only contributing to the problem." Miliband said the safety of British citizens was at risk. "The majority of terrorist attacks in Britain have links back into Pakistan," he said. "There's obviously a large number of British troops and troops from a number of other countries at direct risk in Afghanistan and I think that is a potent brew." Pakistan faced criticism this week over security provided for the visiting Sri Lanka cricket team, after gunmen attacked them as they arrived for a match in Lahore, killing eight people. AFP adds: Australia's Prime Minister Kevin Rudd said Friday his government wanted answers about security failure which led to the ambush of Sri Lanka's cricket team in Lahore. Pakistan authorities have admitted security breaches over Tuesday's attack. Rudd said he was aware of the security concerns "and I am unhappy about them." "I am sufficiently concerned about what has been said by the Australians that we need an explanation, and we intend to get one," he told a radio interviewer.