The Home Secretary has requested the help of the Royal Navy to patrol the English Channel.
It follows the arrest of two men on suspicion of arranging the illegal movement of migrants into the UK.
A 33-year-old Iranian national and a 24-year-old British man were arrested in Manchester on Wednesday evening.
A National Crime Agency spokeswoman said: "NCA officers have tonight arrested a 33-year-old Iranian national and a 24-year-old British man in Manchester, on suspicion of arranging the illegal movement of migrants across the English Channel into the UK.
"As the investigation is ongoing, we are unable to comment further at this time."
The arrests come as it was revealed Home Secretary Sajid Javid has written to the Ministry of Defence to request use of the Royal Navy.
An MOD source told the Press Association that HMS Mersey, an offshore patrol vessel, is "available and ready" to be deployed.
Mr Javid earlier this week announced the redeployment of two Border Force cutters from the Mediterranean.
A Ministry of Defence spokesman said:
"Our Armed Forces stand ready to provide additional capacity and expertise to assist the Home Office with the response to migrant crossings.
"Royal Navy ships continue to conduct patrols to protect the integrity of UK territorial waters."
On Wednesday Mr Javid was criticised for questioning whether migrants using small boats to make risky journeys across the English Channel are genuine asylum seekers.
Speaking on a visit to Dover he said: "A question has to be asked: if you are a genuine asylum seeker, why have you not sought asylum in the first safe country you arrived in?"
He also suggested those picked up by UK authorities faced having asylum requests denied as a deterrent to prevent others undertaking the same dangerous journey.
Foreign Secretary Jeremy Hunt said Mr Javid was right to say that the UK's "proud tradition" of granting asylum is not abused.