"This is about investing in and enhancing the security of the UK border," a government spokeswoman said.
The funding will go towards fencing, CCTV and detection technology in the northern French port city as well as at other points along the Channel from which migrants regularly attempt to reach British shores by ferry or train.
The money would be on top of more than 100 million already paid by Britain following a border deal between the two countries that has now been renegotiated and is due to be signed today.
Macron, who is on his first official trip across the Channel, will meet May at an army base near the British capital.
In a piece of diplomatic theatre, Macron is expected to confirm that France will agree in principle to loan London the Bayeux Tapestry, the famed 941-year-old embroidery that recounts the Norman conquest of Britain in 1066.
"Today's summit will underline that we remain committed to defending our people and upholding our values as liberal democracies in the face of any threat, whether at home or abroad," May said in a statement ahead of the talks.
The leaders are expected to focus on the sensitive issue of immigration.
Hundreds of people continue to camp out in the northern French town, hoping to stow away on trucks heading to Britain, a destination seen as an El Dorado by some migrants from Afghanistan and parts of Africa.
The two countries currently abide by the 15-year-old Treaty of Le Touquet, which permits immigration checks within each other's borders.
A new treaty will be signed at Thursday's summit to complement the 2003 deal, according to French officials.
Disclaimer: No Business Standard Journalist was involved in creation of this content
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
