Labour MP Yvette Cooper asked if Facebook had not taken action against the party and another far-right organisation, the English Defence League, because it had “lower standards” than Twitter.
Mr Milner responded that Britain First had until recently been registered with the Electoral Commission and thus “deemed legitimate” by UK authorities.
He added: “However there are clearly issues with their page on Facebook, there have been a number pieces of content taken down.
“We are obviously reviewing it, but we are very, very cautious about political speech. Very cautious about it”.
Britain First was founded in 2009 by former members of the British National Party and has since garnered a massive audience on Facebook, which is vastly disproportionate to its negligible electoral impact.