Jeremy Hunt is under pressure to take tough action over the disappearance of a Saudi journalist after business leaders shunned the regime.
The Foreign Secretary was warned Britain must not be “craven” in its response to claims Jamal Khashoggi was murdered while visiting the kingdom’s consulate in Istanbul.
Financial Times editor Lionel Barber announced the newspaper is pulling its partnership in a high-profile economic conference in Riyadh, and Sir Richard Branson has frozen several business links with the Gulf state.
Saudi Arabia’s ambassador to the UK Prince Mohammed bin Nawaf al Saud earlier said he was “concerned” about Mr Khashoggi’s disappearance.
Mr Hunt met with the diplomat on Tuesday and later spoke to foreign minister Adel al-Jubeir by telephone to voice the UK’s concerns, but has not spoken publicly about the case since.
Saudi Arabia is Britain’s main ally in the region and Prime Minister Theresa May visited last year.
Former international development secretary Andrew Mitchell warned the UK’s calls for a united international response in the wake of the Salisbury chemical weapons attack means failure to respond to the “vile crime” believed to have been carried out by the Saudis would be “hypocrisy of a very high order”.
He told BBC Radio 4’s The World at One programme: “I spoke to Jeremy Hunt on Wednesday about this and I know that he is deeply concerned and that he is mulling over what Britain should do.
“It is right to investigate it properly before jumping to conclusions, although I have to say those conclusions look pretty clear now.
“I think he is immensely concerned and I have no doubt he will want to speak out when more information is available.
“The point I, and many others, make to the British Government is we should be a candid friend for the kingdom of Saudi Arabia and not a craven friend.
“This is a very important issue now where Britain must react in an honourable way and if we don’t there’s a very great risk to our own reputation as well.”
Lionel Barber, editor of the Financial Times, said the newspaper is pulling out of its official partnership role with the Future Investment Initiative economic conference in Riyadh.
He said: “The Financial Times will not be partnering with the FII conference in Riyadh while the disappearance of journalist Jamal Khashoggi remains unexplained.”
Prince Mohammed said “no-one is overestimating” the seriousness of the situation and “we have made it very clear we would like to know what happened”.
He told the BBC: “We are concerned about our citizen Jamal. There is an ongoing investigation and it would be premature of me to comment until we see the final results of the investigation.”
A Turkish newspaper published the names and photographs of 15 Saudi nationals who allegedly arrived in Istanbul on two private jets the day Mr Khashoggi went missing.
On Wednesday, the Sabah newspaper, which is close to Turkish president Recep Tayyip Erdogan, revealed the identities of what it called a “mysterious” 15-member “assassination squad” who were allegedly involved in the disappearance.
He visited the consulate last Tuesday to obtain a document confirming he had divorced his ex-wife, in order to allow him to remarry.
Turkish officials have said he was killed on the premises and his body removed.
Mr Erdogan has not confirmed the alleged killing, saying he would await the result of an investigation.
Saudi officials have denied the allegations as baseless.
Sir Richard said he would be suspending his directorship of two tourism projects in the country on Thursday, while Virgin would halt discussions with the Saudis over investment in its space projects.
He warned that if fears are confirmed, the West would struggle to continue doing business with the Gulf kingdom.
He said: “What has reportedly happened in Turkey around the disappearance of journalist Jamal Khashoggi, if proved true, would clearly change the ability of any of us in the West to do business with the Saudi Government.”