Brussels - Prime Minister David Cameron said on Tuesday he wants the "closest possible" relations with the EU after Britain voted to leave the bloc, adding the split should be "as constructive as possible".As he arrived at a Brussels summit, Cameron, who is to step down within weeks, told reporters that, while Britain was leaving the EU, "we mustn't be turning our backs on Europe". "These countries are our neighbours, our friends, our allies, our partners," he added."I very much hope we'll seek the closest possible relationship in terms of trade and co-operation and security, because that is good for us and that is good for them."Cameron, who led the campaign for Britain to stay in the bloc, is under pressure from other European leaders to hurry up and file divorce proceedings by triggering the so-called Article 50 of the EU's Lisbon Treaty.But Cameron has said that he will not take this step, which would start a two-year countdown until Britain's departure.He said this was up to his successor, who is expected to take office in September.German Chancellor Angela Merkel said in Berlin earlier on Tuesday that Britain could not expect special treatment and "cherry-pick" in its negotiations."Anyone wishing to leave this family cannot expect to lose all the obligations but keep the privileges," Merkel told the German parliament.