The former Lib Dem leader bashed the Prime Minister after the Tories announced they would replace free school lunches with free breakfasts for all English primary school children
But he called the move “cynical” and said it would offer each child just 7p worth of food.
His party claimed it would lead to 250,000 children living in poverty across England would lose their free meals as a result of the policy.
He told supporters: “Families who are officially categorised as being in poverty will now have those universally free available lunches snatched away from them.
Nick Clegg blasted Theresa May over the pledge in a passionate rant
They [Tories] are being instructed by Theresa May in this heartless, callous, regressive act to snatch those lunches away
“What possible justification can there be, especially when Theresa May talks about helping the ‘just about managing’ when one of the first announcements she makes is to take away lunches from the very struggling families who need the greatest help.
Mr Clegg then called on Conservative candidates to “come clean” and boycott the pledge.
“The Conservatives stood on a manifesto just 24 months ago saying they were going to retain universally available free lunches for children in the first three years of primary school.
“And yet now they’re being instructed by Theresa May in this heartless, callous, regressive act to snatch those lunches away in the manner in which she has described.
Snap election 2017: The pictures politicians may not want you to see Sat, May 27, 2017
Protests, fights and daleks, it's all happening as the politicians hit the campaign trail for the snap election
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Jeremy Corbyn during a visit to Hackney Marshes Football Pitches, to highlight Labour's manifesto commitment to ensure 5% of the Premier League's television rights income is diverted to the grassroots game, during a General Election campaign
“So my challenge to every Conservative candidate is to come clean with voters in each and every constituency in which they’re standing and tell us this: are they going to stand up against Theresa May?”
The criticism comes after the politician pushed for a free school meal policy during his time in government, which meant pupils in reception, Year 1 and Year 2 received free meals regardless of parents’ earnings.
A Tory spokesman told the Evening Standard: “These fears are unfounded and it is disappointing to see them whipped up as a scare campaign.
“Our plans guarantee that every primary school child will have access to a free breakfast at school, which experts say provides the same benefits as a free lunch, and we’ll continue to ensure school lunches are free for those who need them.
“Our proposals are an improvement and are more cost-effective way of improving school meals.”