A Washington Post columnist who went missing after visiting the Saudi consulate in Istanbul was spirited out of Turkey in a private jet and held captive in the kingdom where he may still be alive, a source close to its royal family has claimed to DailyMail.com.

Jamal Khashoggi, a long-standing critic of Saudi Arabia and for the last year a columnist for the Post, has been at the center of international concern that he has been murdered after walking into the consulate in Turkey’s largest city and vanishing.

Turkish police were allowed into the building on Tuesday, a week after Khashoggi vanished, and said that CCTV footage from inside has gone missing and Turkish staff were abruptly told to take a holiday on the day in question, The Guardian reports.

There are fears that the columnist was killed and dismembered inside the embassy before his body was loaded - in boxes - into a waiting van and then flown out of the country in one of two private jets rented by Saudi Arabia.

But a source close to the Saudi royals has told DailyMail.com that an alternative version of events is being discussed inside high levels of the Saudi government.

Allegations: Turkish police believe Mr Khashoggi was tortured and murdered inside the consulate building in Istanbul last week

Flight records show that a Gulf Stream IV private jet, tail number HZ-SK2, landed in Istanbul at 3am on October 2, the day Khashoggi disappeared. Pictured: Flight path the aircraft took

The jet left later that day, stopping in Dubai (pictured) and then flying on to Riyadh. Khashoggi was driven from there to Riyadh, and was held there, the source said

The source said that after entering the embassy Khashoggi was taken in a black Mercedes S-500 and a white minivan with four Saudi officials to Istanbul airport, where he was flown on a private jet to Dubai and then Riyadh, where he is now being held.

Flight records show that a Gulf Stream IV private jet, tail number HZ-SK2, landed in Istanbul at 3am on October 2, the day Khashoggi disappeared.

The jet left later that day, stopping in Dubai and then flying on to Riyadh. Khashoggi was driven from there to Riyadh, and was held there, the source said.

The source was told Khashoggi is still alive, contradicting the claims he was murdered in the Istanbul embassy.

The different version of events cannot be independently verified.

A friend of the columnist also revealed that Khashoggi’s encrypted messages had been read after he vanished.

Though Khashoggi gave his Saudi phone to his fiancée before entering the Istanbul embassy - where he was due to collect divorce papers - he walked in to the building with his T-Mobile US cell phone, which he had used to contact confidential sources.

Embassy officials took the phone and handed it to Saudi intelligence officials, the source said.

Into thin air: This CCTV photo shows the last moment Jamal Khashoggi is seen alive, walking into the Saudi Arabian consulate in Istanbul last Tuesday

The source said that after entering the embassy Khashoggi was taken in a black Mercedes S-500 and a white minivan with four Saudi officials to Istanbul airport. Pictured: Saudi officials gather outside the door where Mr Khashoggi entered last week but never exited

Khashoggi had gone to the embassy to collect divorce papers relating to his previous marriage, leaving his fiancee with his phone on the street outside (pictured)

WhatsApp records show Khashoggi last viewed his messages on his US cell phone at 1.06pm on Tuesday, around the time he entered the embassy.

However, texts sent to him after that time marked as unread cannot be deleted by the sender, suggesting the texts have since been read via software other than the WhatsApp phone app.

On Monday President Trump said that he was 'concerned' about reports on Khashoggi's disappearance.

'I am concerned about that,' Trump said. 'I don't like hearing about it and hopefully that will sort itself out. Right now, nobody knows anything about it.'

'There's some pretty bad stories about it. I do not like it,' he added.

Saudi Arabia's ambassador to the US, Prince Khalid bin Salman bin Abdulaziz, said claims Khashoggi had been killed or detained by Saudi authorities were 'absolutely false, and baseless,' according to a statement provided to CNN.

On Monday President Trump said that he was 'concerned' about reports on Khashoggi's disappearance

'There are many facts regarding his whereabouts that will hopefully be revealed through the ongoing investigation.

'Despite that, we have seen over the last few days various malicious leaks and grim rumors flying around about Jamal's whereabouts and fate,' the statement says.

'I assure you that the reports that suggest that Jamal Khashoggi went missing in the Consulate in Istanbul or that the Kingdom's authorities have detained him or killed him are absolutely false, and baseless.'

Earlier Monday, Turkish President Recep Tayyip Erdogan said Saudi Arabia needs to prove that Khashoggi has, in fact, left the Saudi consulate in Istanbul.

'He entered the general consulate himself, and if he has entered by himself and if he did not exit it, of course this should be proven by the general consulate,' said Erdogan at a press conference in Budapest.