Pittsburgh (AFP) - President Barack Obama on Thursday decried America's "wild, wild west" media environment for allowing conspiracy theorists a broad platform and destroying a common basis for debate.

Recalling past days when three television channels delivered fact-based news that most people trusted, Obama said democracy require citizens to be able to sift through lies and distortions.

"We are going to have to rebuild within this wild-wild-west-of-information flow some sort of curating function that people agree to," Obama said at an innovation conference in Pittsburgh.

"There has to be, I think, some sort of way in which we can sort through information that passes some basic truthiness tests and those that we have to discard, because they just don't have any basis in anything that's actually happening in the world," Obama added.

His remarks came amid an election campaign that has seen Republican candidate Donald Trump repeat ideas and take on key staff from right-wing media outlets.

They also come at the end of an eight-year presidency in which Obama has been plagued by false scandals over his place of birth that have forced him to play media-critic-in-chief.

For much of that time, Republicans and Democrats -- which their own media sources -- could rarely agree on even the most basic facts to build a debate.

"That is hard to do, but I think it's going to be necessary, it's going to be possible," he added.

"The answer is obviously not censorship, but it's creating places where people can say 'this is reliable' and I'm still able to argue safely about facts and what we should do about it."