Hastings Police believe that a small group of suspected illegal immigrants may have left the beach near Rock a Nore this morning after crossing the channel overnight in two rigid inflatable boats.
It is thought they came ashore at Hastings and further east near Winchelsea Beach.
In total 17 migrants, including men, women and children, have been detained by immigration officials, but others are thought to have disappeared into the surrounding countryside.
Detective Inspector Jon Gillings, of Hastings police, said: “Two of those detained required medical treatment and we are concerned that one or two others still outstanding may also be in need of assistance.
“We would ask anyone seeing strangers in the area who may appear cold, wet, hungry, disorientated, or in need of medical aid, to report it by calling us immediately on 999, quoting serial 276 of 03/10.”