French police said Saturday around 300 migrants in Calais attempted to reach Britain via the Channel Tunnel overnight, a significant drop from previous nights after security in Calais was beefed up.
On Thursday night, French authorities faced more than 1,000 attempts by migrants camped out in the port of Calais to reach the undersea tunnel.
That number was already significantly down on the more than 2,000 daily attempts by migrants to breach the defences recorded earlier in the week.
Ten migrants have died attempting to smuggle across the Channel to England since June.
France this week sent 120 additional police officers to the northern port city to stem the crisis.
A spokesman for Eurotunnel, operator of the trains that link Britain and France through the tunnel, said there was "much less disruption" at its terminal near Calais since the reinforcements arrived to bolster a 300-strong existing police contingent.
Late Friday the first attempts under cover of encroaching darkness began at around 9:00 pm (1900 GMT) when a group managed to access the embarkment lanes before being chased off by police.
At around 2:00 am Saturday some 150 migrants were escorted back towards Calais.
In such cases the vast majority seeking to get over to Britain just hide away and await another chance to sneak over.
One man died in the early hours of Wednesday, apparently crushed by a lorry as he tried to make it into the tunnel.
"I didn't make it into the station this time... It was very difficult, there was much more security than on previous days," said 20-year-old Reza from Afghanistan, rubbing his eyes after a short night's sleep as he stepped out of his tent.
"We didn't have a chance last night. There were too many policemen, even more than before," said Baby, 27, from Eritrea, who has been camping out in Calais for more than two years.
Teski, a 29-year-old Eritrean who has twice been escorted out of the Eurotunnel approach area, said that even if someone manages to sneak aboard a train they cannot be sure of getting across the Channel.
"While the train hasn't left you can't say you've done it, even if you're well hidden," he said.
A police source told AFP that, while the reinforcements had helped, "the pressure of the migrants was still there".
Around 3,000 people from Africa, the Middle East and Asia are waiting in Calais to cross into Britain illegally by clambering onto lorries and trains.
Adding to the Calais difficulties, hundreds of French sailors blocked the city on Friday, using burning tyres to prevent access to the port in the midst of the peak holiday travel period.
The roughly 300 workers from French company Scop SeaFrance were protesting plans to sell off some of their ferries to rival Danish firm DFDS, a move expected to result in hundreds of job losses.
The crisis has become a hot political issue on both sides of the Channel.
British Prime Minister David Cameron and French President Francois Hollande discussed the situation by phone on Friday night.
"They both expressed concern about the immediate security challenges and reiterated their commitment to continue working closely together to tackle the problems posed by illegal migration," a statement from Cameron's office said.
Cameron promised "more fencing, more resources, more sniffer dog teams" to aid French police after a meeting of his government's COBRA emergency committee on Friday, at which he warned the crisis could last all summer.
London's aid includes a pledge of £7 million (10 million euros, $11 million) to improve fencing around the Eurotunnel rail terminal in Coquelles, outside Calais.
Divided public opinion on the issue of immigration sparked small rival protests in the British port town of Folkestone, at the mouth of the Channel Tunnel on Saturday, with those welcoming migrants in one camp and far-right wingers opposed to their presence in the other.
"We are here to make it clear to the migrants that many people here would welcome them and that the way they are being treated is not in our name," said Bridget Chapman, organiser of the pro-migrant demo.
But nearby right-wingers chanted: "Britain first, taking our country back."
"British people don't want immigration," said Paul Golding, leader of the Britain First party.
"We are a small overcrowded island. We haven't got enough space for our own people, let alone a torrent of mass immigration into this country."