More than 70 people were intercepted in one day as they crossed the English Channel on eight boats, the government has confirmed.
HM Coastguard assisted UK Border Force off the south coast, as a total of 74 migrants tried to reach the UK.
Conservative MP for Dover and Deal, Charlie Elphicke, said it was "a record number of boats in a single day".
"[This] is deeply concerning and I'm receiving regular updates," Home Secretary Sajid Javid said.
"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."
Last month, 140 migrants were picked up - the highest number since December, when a "major incident" was declared by Mr Javid.
If confirmed this would be a record number of boats arriving in a single day. 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. https://t.co/5YGBEMcmLn— Charlie Elphicke (@CharlieElphicke) June 1, 2019
"[Since December] two cutters have returned to UK waters from overseas, I've agreed a joint action plan with my French counterpart and increased activity out of the Joint Coordination and Information Centre in Calais," Mr Javid continued.
"It is an established principle that those in need of protection should claim asylum in the first safe country they reach and since January more than 30 people who arrived illegally in the UK in small boats have been returned to Europe.
"We will continue to seek to return anyone who has entered the UK illegally.
Earlier in the day, eight men in an inflatable dinghy were spotted on Winchelsea Beach, in East Sussex.
"This crisis was meant to have been dealt with at Christmas, yet numbers continue to rise," Mr Elphicke said.
"The Home Office needs to get a grip."
He said he would be meeting Mr Javid on Sunday.
The Maritime and Coastguard Agency said RNLI lifeboats from Dover, Dungeness and Rye had been involved in the incidents, along with coastguard rescue teams from Folkestone, Langdon and Rye Bay.
A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.