Tata Steel's sale of its loss-making UK businesses has put tens of thousands of jobs in steel manufacturing and the wider supply chain at risk.
Following the meeting with Cameron, Roy Rickhuss, general secretary of Community, the steelworkers’ union, said: "We welcome the Prime Minister’s visit to Port Talbot today."
"As soon as I returned from the Tata board meeting in Mumbai, I asked him to meet and I am pleased he has now taken the time to do so."
The government has said it could take a 25 per cent stake in any rescue of Tata Steel’s UK operations with the government providing debt finance worth hundreds of millions of pounds to potential buyers.
Stuart Wilkie, Tata Steel UK's director at Port Talbot and Llanwern, is also working on plans for a management buyout.
"David Cameron has now joined the growing list of senior politicians who have visited Port Talbot, but today we made it clear that steelworks throughout England and Wales are also under threat," Rickhuss added.
"This is a national industrial crisis and the Prime Minister needs to act nationally and indeed globally to secure a sustainable future for the UK steel industry."