A new border security force is needed to protect the UK from criminal gangs, according to senior police officers.
The police recommendations have been submitted to the government
The proposed force should be formed from the various agencies who currently guard airports and seaports.
Details of the proposal come a day after the government announced plans to toughen immigration laws.
The force was one of 21 recommendations by the Association of Chief Police Officers (Acpo) to the government on tackling international crime.
It would deal with such crimes as drug smuggling, money laundering and people trafficking.
On Monday a consultation paper was published by the government which included plans to punish asylum seekers who have destroyed their passports, and plans to shorten the appeals process and restrict access to legal help.
As crime patterns have changed significantly in the past ten years, the government is looking at ways of dealing with criminals who operate across borders.
Acpo president Chris Fox said the new unit to deal with serious and organised crime could involve the National Crime Squad, the National Criminal Intelligence Service, the Serious Fraud Office and Customs.
In some cases it would replace these organisations, and it may involve MI5 and MI6 in some form, he added.
"It would be a law enforcement agency not a policing agency," he said.
Mr Fox said it had not been decided who would be suitable to oversee such a unit.
He said: "The home secretary remains responsible for the rest of territorial policing
but serious and organised crime should be the responsibility with
cross-departmental responsibility answering to the prime minister."
Any such unit would have thousands of investigators, he said, but its exact
size would depend on the priorities set by government.
The proposals, which Acpo submitted to the government last month, also suggested that people trafficking and identity theft should become specific offences to make it easier for police to secure convictions.