Theresa May has restated her commitment to cutting annual net migration to a “sustainable” level in the tens of thousands.

Questions were raised about whether the commitment would feature in the Conservative manifesto for the upcoming general election, after a Cabinet minister suggested that the issue was “not about numbers” but about ensuring Britain had the skilled workers it needs.

But speaking during an election visit to Enfield, in north London, Mrs May insisted: “We want to see sustainable net migration in this country.

“I believe that sustainable net migration is in the tens of thousands.

“Leaving the European Union enables us to control our borders in relation to people coming from the EU, as well as those who are coming from outside.”

Mrs May has been coming under pressure to confirm that David Cameron’s controversial pledge will feature in the Tory manifesto. She has always maintained her support for the target of reducing net migration – the total amount of incomers to the UK each year minus the number leaving the country – below 100,000, despite failing to hit it during six years as Home Secretary.

Earlier on Thursday, Culture Secretary Karen Bradley told Sky News: “What we need is to have the right people, to attract the brightest and best.

Election 2017 result projection with 49 days to go graphic

“It’s not about putting numbers on it, it’s about making sure we can deliver where industries need skills, where the brightest and best want to come to Britain.”

A spokesman for Ms Bradley later said she was not speculating about what might be in the Conservative manifesto and that the Government commitment had not changed.

Mrs May’s visit to a security equipment supplier came as election campaigning got under way with Jeremy Corbyn’s first major speech of the campaign, in which he pitched the contest as a battle of “the Establishment versus the people”.

The Labour leader promised to overturn a “rigged system” which allowed the rich and powerful to extract the nation’s wealth from the pockets of ordinary working people.

But he was forced to rule out calling a second referendum on Britain’s membership of the European Union following the completion of negotiations, after appearing to dodge the issue when taking questions from the press.

Having initially said only that Labour’s policy would be laid out in the party’s manifesto, he later issued a statement to say: “A second referendum is not our policy and it won’t be in our manifesto”.

The Labour leader accused a “morally bankrupt” Conservative Party of seeking to preserve Britain’s “rigged system”, while cutting public services and blaming migrants and the unemployed for the woes of the economy.

Controversial business figures like Mike Ashley of Sports Direct, Sir Philip Green, Southern Rail and tax-avoiding multinationals should be “worried” about the prospect of a Labour government, said Mr Corbyn, who insisted the result of the June 8 election was not a “foregone conclusion”.

“Those are the people who are monopolising the wealth that should be shared by each and every one of us in this country,” he said.

“It is wealth that should belong to the majority and not a tiny minority.”

Mr Corbyn’s speech came amid speculation about Labour’s taxation plans, after shadow chancellor John McDonnell suggested the wealthy, who he defined as earning over £70,000 a year, should “pay their way more”.