He said his government's position would leave Britain in a "miserable, permanent limbo".
Britain's former foreign minister Boris Johnson has accused Prime Minister Theresa May of betraying millions of Brexit voters and has urged the government to rethink its strategy, adding that the country would never again have the chance to get it right.
Johnson, who led the main Brexit campaign in the 2016 referendum, resigned this month over May's strategy, triggering the government's biggest crisis since she lost her parliamentary majority after calling a snap election last year.
But he claimed in his resignation speech to Britain's parliament on Wednesday that “it is not too late to save Brexit."
Johnson urged parliament to rethink its strategy, adding that the country would never get the chance to do it right again.
He signalled that “the problem is not that we’ve failed to make a free trade agreement, the problem is that we haven’t tried.”
And Johnson said he was unable to support the government's revised Brexit policies agreed on at cabinet level at the prime minister's retreat Chequers two weeks ago.
He added that a “needless fog of self-doubt” had descended over the past 18 months but still praised Prime Minister Theresa May for her speech at Lancaster House on free trade.
However, he said that the real aim should be “that glorious vision of Lancaster House - not that miserable, permanent limbo of Chequers."
“We need to aim explicitly to the vision of the Lancaster House to do free trade deals for the prosperity of the British people,” he added.
Theresa May's government only narrowly won three votes in parliament on trade and customs arrangements this week after rebellions by pro-European members of her party.
Many Brexit or "Leave" campaigners feel they are losing ground to voices questioning the meaning of the 2016 vote, a debate which has deepened divisions and prompted some to predict a Brexit betrayal.
Johnson warned against making the "the fatal mistake of underestimating the intelligence of the public" by saying one thing to the EU and pretending to do another thing to the public.
You can re-watch Johnson's speech here