David Cameron says nearly half of Welsh trade is with the European Union and the nation will be "better off" if the UK remains in.
Treasury officials have estimated that around 100,000 jobs in Wales could be linked to exports to EU countries.
The Prime Minister is visiting Wales in the latest campaign stop to persuade voters that Britain should remain part of the 28-member bloc.
My view is clear: we are better off, safer and stronger in the EU. Wales will be better off because businesses will continue to have full access to the free trade single market.
It is this market of 500 million consumers that brings jobs, investment and lower prices. The single market brings jobs because it's our trade with Europe that helps Welsh businesses to grow and take people on, especially in key industries like energy, aerospace, pharmaceuticals, and high-tech manufacturing
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