The Liberal Democrat leader Sir Ed Davey has blamed Brexit for the continuing migrant boat crossings, and accused both Reform UK and the Conservatives of “exploiting” the issue for their own benefit.

Sir Ed was speaking during a round of interviews with BBC local radio stations ahead of his party’s annual conference which starts on Saturday.

Now in his seventh year as party leader, he answered questions on immigration, the cost of living, pensions, crime, and the Lib Dems’ record in local government.

On the numbers of migrants crossing the English Channel in dinghies, he said: “We didn’t have the small boats problem before Brexit. It’s been caused by the Conservatives… caused by Nigel Farage.

“They should hang their heads in shame. And what really irritates me, is they exploit it for their own political benefit. And I think that’s really wrong.”

The Lib Dem leader is calling on the government to open negotiations with the EU Commission to join its pact on migration and asylum. Sir Ed said that scheme would allow migrants to be returned to whichever EU state they had travelled from – as had been permissible before Brexit – calling it “an effective deterrent”.

He said: “When you see something working you want to be part of it. And if it would give us the right to return everyone who came in small boats, surely we’d want to do that, wouldn’t we? It worked before. And if you want tough action, the Liberal Democrats are offering it.”

Latest figures show that under the current Labour government, small boat arrivals are down by 44% and deportations up by 8%.

However, Sir Ed said that “wasn’t anywhere near enough” and had been achieved only through international cooperation – of which he wanted more.

The Lib Dem leader promised his party’s autumn conference would be a “serious” event.

He told BBC Radio Kent the party would talk about “problems like the cost of living, which is so damaging, and we’ve got a real plan to deal with that. I’ll be unveiling all the measures we have to help people who are struggling so much at the moment.”

He had earlier told listeners to BBC Radio Shropshire that his party would not support abolishing the triple lock on pensions, arguing it was still “sustainable.”

Introduced in 2011, it guarantees that the state pension will increase by either average wage growth, inflation or 2.5% – whichever is highest.

All the major parties currently back the triple lock, but with the public finances under severe pressure and many young people struggling to find employment, there have been calls from some for a rethink, and for the money saved to be used elsewhere.

However, Sir Ed said the triple lock had done much to reduce pensioner poverty, and this could be done “at the same time as giving hope and employment to young people”.

The Lib Dem leader was separately pressed by BBC Radio Cambridgeshire on the question of large donations in politics.

Until Reform UK received two £36m donations last week, the record figure for a party to be given was the £8m the Lib Dems accepted from Lord Sainsbury in December 2019.

Sir Ed said: “I think there needs to be a cap on donations. I have argued that my entire life. We tried when we were in government [in coalition with the Conservatives], and unfortunately a combination of Labour and the Conservatives prevented us getting those votes through.”

Defending donations his party has previously received, he added: “The others were getting huge amounts from their donors. While the rules are different, we have to play by the rules, as the others are playing by those rules. I want to change the rules.”

During his round of interviews, Sir Ed was also pressed on his party’s record in local government. On each occasion, he asked for more time for his councillors – telling presenters on BBC Radio Shropshire, WM, and Somerset that there was “no magic wand” to instantly turn around councils the Lib Dems had recently taken over from other parties.

Nationally he claimed the Lib Dems were in their strongest position for more than a century.

Looking ahead to the next general election, Sir Ed said in some areas only his party could stop Reform UK – claiming it was the Lib Dems’ “moral responsibility” to stop Nigel Farage’s party and what he called their “nasty policies”.

He added: “A lot of people are really worried about Reform… their increasing racism and approach to dividing people up without any practical policies.

“They worry that big money is coming into British politics and foreign interference through Reform. People are worried and they don’t like it.”