Investigators reportedly believe that Mr Khashoggi's body might have been smuggled out of the consulate in diplomatic vans and then carried onto one of the planes.
The UN Office of High Commissioner for Human Rights (OHCHR) has called of an independent inquiry into the suspected "enforced disappearance" on October 2 of a Saudi journalist, Jamal Khashoggi.
US Secretary of State Mike Pompeo also called on the Saudi government on Monday to support "a thorough investigation" of Khashoggi's disappearance, and to be transparent on its results.
He said he was personally following the case but had no new evidence to table.More news: Meghan Markle not sick on royal tour
Turkey's Foreign Ministry spokesman Hami Aksoy said the investigation was "continuing intensively". The Turkish private NTV television said Ankara requested permission for Turkish investigators to search the consulate building in Istanbul. He told local radio in his home state Tuesday that he wants to end the arms shipments if there's "any indication" the Saudis are "implicated in killing this journalist that was critical of them".
The United States and other Saudi allies have taken a cautious approach toward Khashoggi's disappearance, refraining from any strong comments against the oil-rich kingdom.
Secretary of State Mike Pompeo echoed his comments in a statement late Wednesday, saying there were "conflicting reports", but that the USA was "concerned" by Khashoggi's disappearance.
Secretary of State Mike Pompeo also said USA officials have raised the matter with their Saudi counterparts.
It's been nearly a week since Jamal Khashoggi, a prominent Saudi journalist, vanished after entering the Saudi Consulate in Istanbul.More news: Exploding toilet tanks prompt recall of pressure-assisted flushing systems
Allegations that Saudi Arabia killed a journalist inside its Istanbul consulate have forced Donald Trump into a position he never expected - raising human rights with the kingdom he has steadfastly supported.
Mr Khashoggi had been living since previous year in the USA, in a self-imposed exile, in part due to the rise of Saudi Crown Prince Mohammed bin Salman, the son of King Salman. Khashoggi had gone to the consulate to obtain documents needed to marry his Turkish fiancee.
"The Saudi authorities must immediately give a full and credible accounting of what happened to Khashoggi inside its diplomatic mission", Mahoney said. "We will not spare any effort to locate him, just as we would if it were any other Saudi citizen", it said.
Meanwhile, press freedom groups and human rights organizations continued their call for more information about Khashoggi's case and his alleged slaying. She told the newspaper, "I can not think such an incident is acceptable to happen in Turkey". "Saudi Arabia must return to supporting the Syrian revolution and partnering with Turkey on this".More news: Oldest intact shipwreck known to mankind found in Black Sea
Erdogan told reporters on Sunday that authorities were examining camera footage and airport records as part of their investigation. While the Guardian did run a column about Khashoggi on its front page, some Twitter users noted that it seemed like the newspaper was trying to downplay the story by not making it the main focus. The Lebanese al-Akhbar newspaper said that the journalist had been flown to Saudi Arabia with the apparent consent of the Turkish intelligence authorities.