The French may not start intercepting migrant dinghies during the peak crossing months this year, Yvette Cooper hinted.
The Home Secretary said Paris will finally stop boats leaving "in the next few months" and admitted "we need that French action in the water" to end the Channel crisis.
Ms Cooper said French laws blocking police from intercepting migrants once they are in the water are a "serious problem".
It comes as 300 crossed the Channel on Tuesday, less than 24 hours after 601 were detected on 10 boats - taking the total to more than 12,700.

The Summer months - particularly August and September - are considered the peak for people smugglers, when the Channel is calmer.
Home Office sources had privately been hoping Paris would begin operations to block boats in the water at the end of this month.
But the Home Secretary told LBC: "We hope that the work that the French are doing means that they will start taking action within French waters over the next few months.
"I think that is hugely important. We're obviously pressing them to do that as swiftly as possible. And then the counter terrorism powers will come in later this year.
"At each stage, we are increasing the enforcement, the work with other countries, the work with Europol, on those gang networks, because they do spread right across Europe as well."
People smugglers have adapted their tactics because they know the French police won't intercept them in the water.
The crime gangs launch a boat further down the coast and pick up asylum seekers already standing in the water, with officers watching on.
Ms Cooper said: "Once everybody is in the water, the French authorities do not intervene. That is a serious problem. Soon as it's in the water, their rules meant they weren't taking action. That's a serious problem.
"So the UK governments have been asking France to change their position for very many years, and they have now finally agreed to do so as a result of the work we've been doing with them.
"That is important, but it's not enforced yet. So don't get me wrong, this continues to be a really deep-rooted problem, because those criminal gangs have had six years to take very deep roots.
"But we need that French action in the waters, not just on the coast, and we also need the broader counter terrorism powers that we're bringing in."
More than 12,400 migrants have crossed the English Channel so far this year, Home Office figures have revealed.
It came as 601 people in 10 boats made the treacherous voyage on Monday - the day Prime Minister Sir Keir Starmer announced an immigration crackdown.
Home Office figures show 12,407 have crossed in 224 boats, with 1,333 arriving in May alone. And at least 300 migrants are believed to have made the crossing today.
Border Force vessel Typhoon brought in a group of people this morning after it responded to two incidents in the Channel. It set off in the early hours before making a detour stopping mid-Channel between Folkestone and Wissant.
It then set off further down the Channel until it stopped around 9am again between Lydd and Boulogne, according to satellite tracking site Marine Traffic before heading back to Dover.
Hurricane also dropped off another group of people this morning at the port's Western Docks.
BF vessels Defender and Ranger were also involved in rescues. They were seen in the middle of the Dover Staits in the morning close together along with two search and rescue rhibs between Dover and Calais.
Weather is expected to deteriorate with stronger winds picking up which is expected to thwart further crossings.
Labour's plan to end the Channel migrant crisis passed its latest Commons hurdle on Monday night, despite pleas for the Government to take a tougher stance.
The legislation aims to introduce new offences and counter-terror-style powers to tackle people smugglers bringing migrants across the English Channel.
People selling and handling boat parts suspected of being used in migrant Channel crossings could face up to 14 years in prison and the Government wants to make it an offence to endanger another life during sea crossings to the UK.
But Shadow Home Secretary Chris Philp said: "The numbers in asylum hotels have gone up by 8,000 so far under this Labour Government.
"Speaking of removals deterrents, I was in Berlin four or five weeks ago talking to members of the CDU party, which is now in Government.
"The incoming German Government intends to implement a removals deterrent very similar in concept to the Rwanda scheme.
"So other Governments around the world have realised that they have to do this; it worked in Australia, and the new German Government will be doing something very similar.
"It is just our Government who are going headlong in the opposite direction."
Former minister Esther McVey added: "The reality is that until this Government get ahead of the curve, get a spine, take the UK out of the ECHR, repeal the Human Rights Act-a law that Labour introduced to cement the ECHR in British law-reinstate the Rwanda scheme and radically clamp down on housing and benefits, I am afraid that immigrants will continue to come to the UK.
"The British people expect security and prosperity, not platitudes and broken promises."
A Home Office spokesperson said: "We all want to end dangerous small boat crossings, which threaten lives and undermine our border security.
"The people-smuggling gangs do not care if the vulnerable people they exploit live or die, as long as they pay and we will stop at nothing to dismantle their business models and bring them to justice.
"That is why this government has put together a serious plan to take down these networks at every stage.
"Through international intelligence sharing under our Border Security Command, enhanced enforcement operations in Northern France and tougher legislation in the Border Security, Asylum and Immigration Bill, we are strengthening international partnerships and boosting our ability to identify, disrupt, and dismantle criminal gangs whilst strengthening the security of our borders."
You may also like
Donald Trump ends bizarre speech in Saudi Arabia with gay anthem YMCA
Daniil Medvedev turns on Italian Open crowd before Lorenzo Musetti match suspended
Maya Jama confirms Ruben Dias relationship as they make huge public statement
UK homeowners urged to leave bay leaves around kitchen
Punjab's Majitha hooch tragedy: 17 dead, several hospitalised; CM Mann announces Rs 10 lakh ex-gratia