Between 150 and 200 migrants have been intercepted by Border Force officials while trying to cross the Channel on Sunday, Sky News understands.
A number of crafts were stopped throughout the day, with those inside, which included children, being brought ashore.
Photos also appear to show people on RNLI boats landing in Dover, Kent.
Sky News has approached the Home Office for comment.
Nearly 6,000 people have reached the UK in the first six months of the year, according to analysis by the Press Association, with last year’s record-breaking number of 8,417 set to be eclipsed if the crossings remain at their current rate.
The increase in people trying to make the perilous crossing comes as Home Secretary Priti Patel announced that those trying to reach the UK, as well as people-smugglers, will face heavier prison sentences, in an effort to prevent “asylum shopping”.
The new enforcements will form part of the Nationality and Borders Bill, which will get its first reading in Parliament on Tuesday, as part of Ms Patel’s pledge to “fix” what she called the UK’s “broken asylum system”.
If the legislation is passed, it will become a criminal offence to knowingly come to the UK without permission and could land those found guilty in prison for up to four years.
People smugglers could face life behind bars under the same laws – up from 14 years.
The Home Office claims that migrants are allegedly “picking the UK as a preferred destination over others”, rather than claiming asylum at countries they arrive in earlier.
According to aides, the law will be designed to allow those who are intercepted in British waters to be brought ashore and prosecuted.
Officials said the draft law was about “sending a clear message to migrants thinking about paying people smugglers to make dangerous and illegal journeys to the UK”.
Ms Patel said: “Our new plan for immigration is fair but firm.
“We will welcome people through safe and legal routes whilst preventing abuse of the system, cracking down on illegal entry and the criminality associated with it.”
At the 2019 election, the Conservatives pledged to reform the immigration system, describing as “broken” and “overwhelmed”, while Ms Patel said she wanted to tackle “illegal migration head-on” in March.
Steve Valdez-Symonds, Amnesty International UK’s refugee and migrant rights director, said: “While the Home Office continues to make no safe and legal routes to the UK available for those claiming asylum, some people will continue to be forced to risk their lives to do so – including in small boats across the Channel.
“Instead of peddling deliberately misleading myths and untruths about asylum and migration, the Home Office should be establishing safe routes for those few people escaping persecution who wish to seek asylum here.”