This is a new joint police command to target human traffickers and 10 million euros ($11.2 million) in new British government money to help asylum seekers and send others back home.
The measures are aimed at overcoming diplomatic and economic tensions around the French port of Calais, a flashpoint in a European summer marked by unusually large waves of migrants.
British Home Secretary Theresa May and French Interior Minister Bernard Cazeneuve visited the tunnel Thursday announced plans for a "substantial" increase of security guards, higher fences, surveillance cameras, floodlighting and infrared detection technology.
Since the start of June, at least 10 migrants have died trying to sneak through the Channel Tunnel to Britain. Countless others have slipped through undetected on trucks. Britain and France have accused each other of not doing enough to manage the migrants.
An estimated 3,000 migrants are camped in Calais with more arriving daily, drawing intense political attention in Britain. Elsewhere in Europe this year, Germany has seen 360,000 migrants arrive and 160,000 migrants have reached Greek shores.
May insisted on the importance of distinguishing between refugees fleeing war and repression and migrants coming illegally to seek better economic prospects.
"It's a problem that starts elsewhere in the world with migrants trying to come abroad with organized criminal gangs," she said Thursday.
Britain will increase monitoring of other North Sea ports as the crackdown on Calais pushes migrants to other potential departure points, she said.
The two countries announced a new joint police command center to coordinate intelligence to disrupt migrant-trafficking gangs.
The overall cost of the measures was not disclosed. But a joint statement said Britain would provide an additional 5 million euros a year for the next two years for identifying and protecting the most vulnerable migrants, particularly women and children — and on sending economic migrants home.
British border guards will meet with migrants to provide "a more dissuasive and realistic sense of life for illegal migrants in the U.K.," the declaration said.
Cazeneuve said French authorities have dismantled 19 trafficking networks this year.
There are now about 400 surveillance cameras, 200 French guards and 500 other French security forces surrounding the area near the tunnel entrance, British officials said.
Britain has financed four-meter-high (13-feet) border fences that Eurotunnel spokesman Romain Dufour says have reduced migrant storming considerably. The number of attempted tunnel crossings has dropped to about 150 a night since emergency security measures were put in place, down from a height of about 2,000 in late July, Eurotunnel says.
France will also strengthen support for aid groups and local officials helping the most vulnerable migrants, Cazeneuve's office said. The minister emphasized the "human dramas" driving people to make the treacherous journey.