He said Brexit would create an "economic rupture" with jobs lost and businesses closed, undoing the progress made since the financial crisis.
“When those who want Britain to leave the EU complacently wave away expert predictions of an economic shock, or casually dismiss the warnings of British businesses that employ millions of workers, I think about what that would mean for families who are striving day by day to improve their circumstances. And I am troubled by how relaxed they are about the real life consequences of the economic rupture that is at the heart of their position,” Crabb told the Sunday Telegraph.
“Lost jobs and livelihoods take an enormous, indelible toll on families and communities. No one should be complacent about the potential consequences for working people and their families if Britain votes to exit the EU. This is not a theoretical debate,” said Crabb.
Campaigning officially kicked of this weekend ahead of the vote on 23 June.
Brexit backer Boris Johnson on Saturday launched a fresh attack on the Prime Minister David Cameron over spending millions on pro-EU leaflets and accused Barack Obama of hypocrisy on the EU. The US President is expected to share his thoughts on the referendum on a visit to the UK this week.