It is understood that parliamentary staff were told to expect a visit by minor royals taking part in an official Saudi delegation to the UK ahead of a round-table meeting International Trade Secretary Liam Fox and Baroness Fairhead, it is understood.
The venue was later switched to outside the parliamentary estate, with MPs threatening to protest against the event.
Saudi crown prince Mohammed bin Salman, who has met the Queen, the Prime Minister and the Archbishop of Canterbury as part of a three-day visit to the UK, has launched social reforms in the conservative kingdom but faces continued criticism over the rights of women.
On Thursday, the Archbishop of Canterbury Justin Welby met Mohammed bin Salman at Lambeth Palace, with charities calling on the Anglican leader to raise concerns over Saudi Arabia’s role in the war in Yemen.
Amnesty International UK’s director, Kate Allen, said: “We hope Justin Welby used the meeting as an opportunity to personally communicate the Church’s concerns over the thousands of Yemeni civilians killed and injured in reckless and indiscriminate Saudi-led coalition air strikes.
“We also hope the archbishop was able to express concern over the ongoing jailing of peaceful critics of the Saudi government, including the prisoner of conscience Raif Badawi.”
The meeting with the archbishop came after Theresa May and the crown prince used Downing Street talks to lay out plans for a £65 billion trade and investment package. The Prime Minister raised the situation in Yemen with the Saudi royal.
The crown prince held further talks with Mrs May during a private dinner at Chequers last night.
On Friday, he will meet Defence Secretary Gavin Williamson for talks, amid calls for the suspension of UK arms export licences to Saudi Arabia. The first day of his visit saw the crown prince have dinner with the Prince of Wales and the Duke of Cambridge after a lunchtime audience with the Queen.
Yemen has been embroiled in a bloody civil war since 2014 when rebels took over the capital city of Sanaa.
Saudi Arabia is the main player in a coalition supporting the Yemeni government against the Houthis in a war which has caused a humanitarian catastrophe.
The crown prince has initiated a modernisation programme, Vision 2030, but the reforms have been dismissed as a “mirage” by human rights campaigners. According to human rights charity Reprieve, executions have doubled under his rule.