An Iranian national and a British man have been arrested on suspicion of arranging the “illegal movement of migrants” across the English Channel into the UK.

The National Crime Agency said the Iranian, 33, and the British man, 24, were arrested in Manchester on Wednesday evening.

The arrests come after the home secretary, Sajid Javid, declared a “major incident” over the rising number of people trying to “illegally” enter the UK on boats, and it was reported that he had requested the Royal Navy deploy extra ships to the Channel.

An NCA spokesperson 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 … As the investigation is ongoing we are unable to comment further at this time.”

Following the rescue of a group of migrants on Christmas Day, Javid’s response to the rise in the still relatively tiny number of people attempting the crossing has been criticised by charities as “deeply concerning”, while others suggested it lacked humanity. He was criticised by lawyers and campaigners on Wednesday after appearing to suggest asylum seekers should be deterred by making it harder to gain asylum, which is a right enshrined in international law.

In what would represent a significant escalation of the government’s current approach, a Ministry of Defence source told the Press Association that HMS Mersey, an offshore patrol vessel, was “available and ready” to be deployed.

An MoD 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.”

The Labour MP Stella Creasy, who has visited migrant camps in Calais, said politicians were ignoring the reasons people sought refuge in the UK. “The asylum system in France is completely deadlocked and I fear deliberately so – they should be challenged on that,” she said. “But none of that means Britain can absolve itself of responsibility to refugees.

“People will continue to die and be at the mercy of traffickers all the time politicians pretend to play tough for votes rather than recognise why people flee.”