Video report by ITV News Correspondent Martha Fairlie
More than 70 migrants have been detained after eight small boats tried to cross the English Channel on Saturday, the Home Office confirmed.
Home Secretary Sajid Javid described the incident as "deeply concerning", after the vessels were intercepted by Border Force officials off the Kent coast.
Only one of the eight vessels made it to shore, landing at Winchelsea Caravan Park beach, East Sussex.
Two other vessels were stopped in France by the authorities there.
All those detained have been assessed and cleared by medical staff and are now being processed by immigration officials, the Home Office said.
The Home Office said the nationalities of the detainees are still being determined, and a criminal investigation has been launched.
Mr Javid added: "Those who choose to make this dangerous journey across one of the busiest shipping lanes in the world are putting their lives in grave danger - and I will continue to do all I can to stop them."
He said the UK Border Force had stepped up its activity out of the Joint Co-ordination and Information Centre in Calais.
Mr Javid added: "We will continue to seek to return anyone who has entered the UK illegally."
Earlier Kent MP Charlie Elphicke responded to reports of eight boats carrying migrants being dealt with, claiming it would mean "a record number of boats arriving in a single day".
Mr Elphicke told ITV News: "We need to see the Home Office and the French authorities work together to bring this crisis to an end."
A spokeswoman for HM Coastguard said it had assisted the force with nine vessels on Saturday morning.
Mr Elphicke also said on Twitter: "This crisis was meant to have been dealt with at Christmas, yet numbers continue to rise.
"It looks set to surge to record levels through the summer.
"The Home Office needs to get a grip on this crisis."
HM Coastguard initially said it had assisted Border Force colleagues with 13 vessels, but it said the higher figure was due to multiple reporting as events unfolded.
Border Force vessels, RNLI lifeboats from Dover, Dungeness and Rye and coastguard rescue teams from Folkestone, Langdon and Rye Bay were involved in the response.
Images of men being given blankets by emergency service workers on Winchelsea Beach in East Sussex have been shared on Twitter.
An HM Coastguard spokeswoman said it is "committed to safeguarding life around the seas and coastal areas of this country".
She added: "We are only concerned with preservation of life, rescuing those in trouble and bringing them safely back to shore, where they will be handed over to the relevant partner emergency services or authorities."