Channel migrants deported under Labour’s ‘one in, one out’ deal with France have been sneaking back into Britain hidden in lorries.Eleven people who have re-entered this country by the clandestine route have yet to be removed, it has emerged.Deportation proceedings have been begun against them but so far none has gone back to France, it is understood.It has led the Government to renegotiate part of the agreement with Emmanuel Macron’s government to close the loophole.The new version will specifically cover small boat migrants who are deported from the UK but who then come back concealed in lorries.The Home Office has also confirmed the treaty which had been due to expire next week has been extended until October.So far the UK has removed 921 small boat migrants since the treaty came into effect on August 6. In February last year a group of migrants were found in the back of a French HGV on the M3 motorway, leading to a 10 mile tailbackThis country has accepted 896 asylum seekers from France as part of the reciprocal terms of the deal.In addition to the 11 known migrants who have returned by lorry, there may be other cases but the full scale of the problem is impossible to measure due to the clandestine nature of their illegal entry.Migrants who enter Britain by such methods are often seen emerging from vehicles in motorway service areas or lay-bys when drivers make their first stop after crossing the Channel.The migrants will then vanish into the underground economy and will not be formally logged by the Home Office.There were at least four cases where such journeys were discovered in March, the Times reported, and two in the autumn.In a letter to Laurent Nunez, the French interior minister, Home Secretary Shabana Mahmood said: ‘Following our recent meeting which allowed us to observe the quality of the cooperation established under the agreement I wish to propose an addition to the objectives of the agreement, explicitly adding the objective of deterring clandestine returns to the United Kingdom by individuals previously transferred to France under the agreement.’Last October it emerged that one of the first small boat migrants deported under the scheme returned by dinghy to Britain just weeks later. Home Secretary Shabana Mahmood has now re-drawn the 'one in, one out' deal with France to cover migrants who re-enter Britain hidden in HGVs after being deportedThe Iranian man’s second crossing took place just 29 days after he was kicked out of the country under Sir Keir Starmer’s flagship borders policy.The unnamed man first arrived here on August 6 - the first day the French deal was in force - and was removed from Britain on September 19 on a scheduled flight.But he later skipped a migrant shelter in Paris, where he had been housed, and headed back to the northern French coast.