The UK government has pledged £12m to help France tackle the problem of 'illegal immigrants' trying to enter Britain through Calais.

The deal, announced on Saturday by the home secretary, Theresa May, and France's minister of interior, Bernard Cazeneuve, will also see increased co-operation between the two countries' law enforcement agencies.

Contributions by the UK will be given in the form of €5m (£4m) a year for three years to a joint intervention fund. This money will be used to construct robust fences and to bolster security at the parking area of the port, which migrants use as a staging post for efforts to cross the Channel.

Plans also include the possibility of installing technology to address the dangers of migrants hiding in tankers and refrigerated lorries. Tensions have been growing in Calais in the past year and authorities have been vocal in asking for help with immigration in the port. The French authorities believe there are 1,500 illegal immigrants in the town, a rise of 50% on last year. Many have fled humanitarian crises in Africa and the Middle East.

Two weeks ago around 200 migrants stormed the ferry terminal and tried to board a P&O passenger ship in the hope of making it across the Channel. They were forced back by ferry crew with fire hoses. And last Wednesday, another 250 migrants clashed with police as they tried to force their way on to UK-bound trucks.

In a joint statement, May and Cazeneuve said: "Efforts will be made to strengthen cooperation by establishing permanent joint mechanisms to deliver the comprehensive action plan and enhance co-operation between British and French law-enforcement agencies at the border. This will include helping to identify measures to ensure migrants do not breach the laws of either country or threaten the safety of Calais residents or those using the port. It will also support improved joint returns initiatives and further comprehensive action against those trying to evade immigration control."

Security and immigration minister James Brokenshire added that British and French law enforcement agencies would also target organised crime gangs behind people trafficking and smuggling. "Earlier today the home secretary and French interior minister Bernard Cazeneuve set out a number of joint commitments to tackle problems at the port of Calais, including bolstering security," he said. "Their declaration also reaffirms their commitment to closer working by UK and French law enforcement agencies to target organised-crime gangs behind people trafficking and smuggling.

"The priority now is to implement the practical solutions that have been agreed."

Information campaigns due to start next month will explain the reality of illegal migration and its consequences in the UK and also set out information on asylum in France or assisted voluntary return.

As part of the agreement, the layout of the port will be changed to make it easier to carry out controls and improve traffic flow.

The National Crime Agency will second a full-time office to Ocriest, the French agency responsible for tackling illegal immigration, while the French border police will send two officers each month to work with the joint border intelligence unit in Folkestone.

The ministers also resolved to push for European Union action on an "evident migration crisis" in the Mediterranean Sea.

The deal comes after the mayor of Calais, Natacha Bouchart, announced last month that a new Sangatte-style refugee centre would be opened to house the town's migrants. It will become the first large-scale shelter for Calais migrants since the controversial Sangatte Red Cross hostel was bulldozed in 2002.

That centre was used as a stepping stone to Britain by an estimated 18,000 refugees during its six years of operation.