Cameron, who secured a deal on EU reforms at a summit in Brussels last week, asked lawmakers to favour to stay within the EU to prevent the UK losing its "negotiating muscle" in future trade and investment deals in the event of an exit from the 28-nation bloc.
"We have secured commitments to complete trade and investment agreements with the fastest growing and most dynamic economies around the world, including the USA, Japan and China as well as our Commonwealth allies India, New Zealand and Australia," Cameron told the House of Commons in his speech to officially table June 23 as the date of the in-out referendum in Parliament.
"Country after country have said to me that of course they could sign trade deals with Britain but they also said that their priorities will be trade deals with EU," he said.
Cameron's speech can be seen as an indirect reference to a long-pending Free Trade Agreement (FTA) being negotiated between India and the EU.
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He sought to warn Eurosceptics that the UK's exit would be a "recipe for uncertainty and disaster" for such trade pacts.
The lines have now been drawn between the 'Leave' and 'Remain' camps for the referendum, with as many as 100 MPs of his own Conservative party saying they would back 'Leave' including his Indian Diaspora champion Priti Patel.
The poster boy for the 'Leave' campaign has now emerged as Mayor of London Boris Johnson, seen as a potential successor to Cameron and future prime minister, whose announcement yesterday came as a big blow to the PM.
It is the first time lawmakers have had the chance to question Cameron since Friday's agreement ahead of the referendum in four months' time.