France and Britain vowed Sunday that a cross-Channel migrant crisis was their "top priority" in a united front that belied simmering anger over an issue which has become a political hot potato.
Beefed-up security has curbed the number of attempts by migrants in the port city of Calais trying to make it through an undersea tunnel to Britain, with only 400 bids Saturday night, a police source said, compared to 2,000 earlier in the week.
Around 3,000 people from Africa, the Middle East and Asia are camped in Calais waiting to smuggle themselves into Britain, and the costly crisis has strained ties across the Channel.
"Tackling this situation is the top priority for the UK and French governments," French Interior Minister Bernard Cazeneuve and his British counterpart Theresa May in a statement published in France's Journal Du Dimanche and Britain's Telegraph newspaper.
"We are committed and determined to solve this, and to solve it together."
However, in a sign of the political anger on the ground, a French opposition lawmaker accused British Prime Minister David Cameron of failing to grasp "the severity of the problem".
"If he continues not to propose anything else, let's let the migrants leave and let Mr Cameron handle his politics in his own way, but on his own island," former employment minister Xavier Bertrand told the Journal Du Dimanche.
"The English must change their rules on migrant labour because in England... the reality is that it is possible to work without papers."
At least 10 migrants have died since June in the nightly attempts to find a way onto a train a lorry headed for Britain -- seen as a better economic option by migrants, many of whom do not speak French.
The incursion attempts on Saturday night saw traffic blocked for five hours, a Eurotunnel spokesman said, adding the measure was taken for the security of both clients and migrants.
The spokesman said the migrants had changed tactics and instead of making a dash into Eurotunnel premises in small groups, were attempting to storm security barriers in large numbers.
In Britain, politicians reminded Cameron of the soaring economic cost of the traffic chaos, demanding more compensation from the French.
Acting Labour Party leader Harriet Harman said the crisis was costing hauliers 700,000 pounds (900,000 euros) a day.
"It is wrong for UK businesses and families to face these costs given border security failures in France," she wrote in a letter to Cameron.
"Your discussions with the French government should therefore include a request for compensation backed up by any diplomatic pressure that may become necessary."
Earlier this week, the British government pledged 10 million euros ($11 million) to improve fencing around the Eurotunnel rail terminal in Coquelles, outside Calais.
And Cameron, who has warned that the crisis could last all summer, promised "more fencing, more resources, more sniffer dog teams" to aid French police in their nightly cat-and-mouse game with the migrants.
The new measures sent "a clear message", according to Cazeneuve and May.
"Our border is secure, and there is no easy way into the UK," they wrote.
They said the world was facing "a global migration crisis" that required a European and international response, and warned that the burden of tackling the problem should not lie with Britain and France alone.
"Many of those in Calais and attempting to cross the Channel have made their way there through Italy, Greece or other countries," the pair wrote.
Ultimately, the crisis had to be addressed at the roots by "reducing the number of migrants who are crossing into Europe from Africa" for economic reasons.
"Our streets are not paved with gold," they said, adding that both governments were currently sending back around 200 migrants a month who do not qualify for asylum.
Divided public opinion on the issue of immigration sparked small rival protests on Saturday in the British port town of Folkestone, at the mouth of the Channel Tunnel, 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."
However, the Guardian reported on Saturday that the Bishop of Dover, the Right Rev Trevor Willmott, criticised David Cameron's rhetoric regarding the migrant crisis. Calling out the prime minister's lack of compassion, he stated that "we need to rediscover what it is to be human, and that every human being matters."