New powers for Border Force officers to board boats and arrest anyone they suspect of attempting a clandestine entry to Britain have come into force as part of a package of measures ordered earlier this year by the home secretary, Theresa May.

The boost to the “maritime capacity” of the UK Border Force will include the provision of extra patrol boats and three new maritime hubs to protect Britain’s coastline and deter migrants from making the perilous journey across the Channel.

Downing Street said on Tuesday that increased security at the ferry port and the tunnel in Calais had led some migrants to attempt to use “more dangerous routes” to reach the UK. On Saturday 18 Albanians were rescued from a sinking boat in the Channel.

Chris Grayling, the leader of the House of Commons and a leading Brexit campaigner, said the government would want to show that the UK was not a “soft touch for economic migrants” by taking immediate action to stop any more boats.

“This is a very real issue for us right now. If we leave the EU it will take a bit of time before we do that. I think and I know Theresa May thinks we need to take quick action this summer. I certainly do not want the English Channel becoming the Mediterranean with fleets of small boats coming over.”

Grayling suggested the 18 Albanians

should not be granted asylum. “I would want us to be very vigorous about any application for asylum from Albania,” he said. “Albania is a candidate country of the EU and, unless there is an extremely individual and particular reason for

granting asylum to someone from Albania, I would want to have an

asylum system that treated those people as economic migrants.”

Downing Street moved quickly to insist the UK border was not wide open. “We take every necessary action to protect our border security and will continue to do so,” said a spokesman.

“The important thing is that our approach is intelligence-based. So we have worked with the French government at Calais to secure the border there and since we put security measures in place we have seen a small number of migrants trying to use more dangerous routes to get to the UK.”

The extra maritime measures will include the deployment “in the coming months” of half a dozen extra small patrol boats – probably inflatables – to supplement the Border Force’s three larger cutters.

The smaller rigid-hulled inflatable boats are regarded as a better option than the larger cutters in intercepting small boats like the one used by the Albanians over the weekend, as there is less danger of swamping them.

The boats will not all be fully operational until the end of next year. They will be used to intercept attempts to smuggle dangerous weapons and drugs into Britain as well as preventing clandestine entry by migrants.

The extra boats are only one part of the response. Radar and aerial surveillance play a much bigger role in identifying possible unlawful activity around the coast.

The three extra maritime coordination hubs in Cornwall, the Thames Estuary and the Humber being set up over the summer are designed to improve the use of intelligence and create more flexible response teams including increased coverage of smaller ports.

When the details of the new powers were announced by the Home Office last week before the period of EU referendum purdah began, the immigration minister, James Brokenshire, said: “Our investments and improvements over the past six years have left us with one of the most secure borders in the world. But we know we must go further and continue to adapt and react to the challenges we face.”

May told MPs on 10 May: “The maritime capability of the border force is being changed so that it is more flexible to be able to deal with the issues that we are now looking at and addressing because we are conscious of the need always to ensure that the capability is able to deal with any potential issues that may be coming down the line.”

The announcement of further measures to boost Britain’s maritime security followed warnings earlier this year from unions, the former chief inspector of borders and immigration and the chairman of the Commons home affairs select committee that cutbacks to the UK Border Force were putting security at risk.

Keith Vaz, the committee chairman, said: “The government has been very, very lax. We warned them as soon as they put in extra security at Calais that the problem would disperse to other parts of France, Belgium and Holland. That is exactly what has happened.”