"Britain has seen few more shameful spectacles than Theresa May's tour of the Persian Gulf," George Galloway said on Friday.
In his weekly talkRADIO programme, the former MP commented on Boris Johnson's statement about Saudi Arabia, the same week Prime Minister Theresa May met the King of Saudi.
"May wouldn't be allowed to drive a car in Saudi Arabia, yet she was there to sell them guns and gas," he said.
"Yes, May was there to arm same Saudis who in 2016 have beheaded more people than ISIS, which is set to crucify a 17-year-old."
He said the UK is arming the same Saudi Arabia which is "the fountainhead of global terrorism, as all our leaders admit privately".
But Mr Galloway said something very unusual happened then, with Boris Johnson telling the truth.
"I am second to none in detestation of Boris Johnson, yet if he was good enough when lying he must not be sacked for telling the truth."
He said the way the Prime Minister treated the Foreign Secretar was a "shameful stain on our country".
"Boris Johnson doesn't speak for the the Government? He's only the Foreign Secretary!"
Listen to his full monologue above...