Head teachers in Thanet have called for urgent action to stop large numbers of fostered children from outside Kent being "dumped" in their schools.
They said often the children, regularly from London boroughs, caused "considerable problems".
Thanet has 201 fostered children from inside Kent and 108 from outside the county. Neighbouring Canterbury has 45 from Kent and 35 from elsewhere.
Kent County Council (KCC) said it shared the head teachers' concerns.
Fostering officials in London said they were working with their counterparts in Kent to try to reduce the number of children being sent to schools in the county.
The eight schools covered by the Thanet Heads Group have written to KCC to say "enough is enough".
"The law allows London boroughs and others to place these very vulnerable children in Thanet," said chair Andy Somers, principal of Hartsdown Technnology College in Margate.
"We have to divert a lot of resources to look after them."
Paul Luxmoore, head of Danecourt Grammar School in Broadstairs, said there was an "industry" of fostering in Thanet.
"Kent County Council is advertising for foster carers while at the same time trying to persuade London boroughs to stop sending their children here," he said.
"We are trying to stick up for these looked-after children."
"I understand the need for authorities to find alternative places for them to live and be educated but Thanet is already a very, very deprived area and we question whether it is the place to put vulnerable children of this kind."
Closer to home
The heads said they wanted the government to investigate the issue and a change in the law to ensure the needs of individual children were met.
The county council said it agreed the number of fostered children being placed in Thanet put pressure on services such as schools.
"We are in discussions with the London authorities about where they place their looked-after children," it said in a statement.
"It is our belief many could be in care closer to their home town where they will benefit from familiar surroundings and contact with extended family members.
"We are hoping to make rapid progress with the London boroughs to resolve this."
Andrew Christie, of The Association of London Directors of Children's Services, said, "London boroughs have an ongoing dialogue with Kent County Council about the referrals of children in care.
"The directors of children's services from all London boroughs have been working to reduce the number of children in care across London as a whole and have agreed to work with Kent County Council to reduce the number of children placed in Kent."
He added: "Any referrals of children in care to areas in Kent have been done with the interests and needs of the child at the heart of the decision."