The Omani co-pilot who stabbed his captain in an apparent attempt to crash an Israel-bound flight from Dubai had previously undergone radical Islamist indoctrination and was suicidal, Israel’s prime minister, Benjamin Netanyahu, has claimed.

Israeli passengers intervened to stop the attack on Wednesday, restraining the co-pilot, while a reserve crew in the plane was able to stabilise the plummeting plane and ultimately land it safely in Saudi Arabia.

The plane had more than 170 people onboard and Israeli officials praised the bravery of those who intervened, announcing that four of the Israeli passengers would receive a “heroism” award for preventing a potential disaster.

Netanyahu told Fox News: “We know that he underwent Islamic radical indoctrination. That appears to be something we are gathering from his personal information.”

The co-pilot, whose identity is still not known, was being interrogated by Saudi security services, which arrested him on the plane’s arrival in Tabuk, in the north-west of the country.

Saudi investigators were cooperating with the United Arab Emirates, the US, Oman and Israel to try to determine the attacker’s motive, a regional official familiar with the investigation said. “All possible scenarios, from terrorism to mental disorders, are being looked into. Nothing is ruled out for now,” they told the Associated Press.

Two Israeli security officials said that Israel’s initial assessment was that the co-pilot was probably acting alone, Reuters reported.

Netanyahu said that the co-pilot was probably suicidal, citing preliminary “indications”.

“It looks very likely that he was going to down the plane … The Islamist tendencies, that radicalisation that are found in his background, I think that’s a pretty good clue,” he said, emphasising that final conclusions had yet to be made.

Netanyahu had previously said it was “too early to say” if there was any state backing – namely Iranian – of the attack. Two Israeli security sources told Reuters that they had not yet found Iranian involvement.

The attack came just days after Netanyahu warned of an unspecified security threat to Israel that could come during its October election. The Israeli military had said before the incident it had no specific intelligence of an imminent threat and the opposition leader Yair Lapid said that a security briefing on Tuesday night included no mention of a related threat.

Other Israeli officials, including the defence minister, Israel Katz, and the ambassador to the UN, Danny Danon, suggested the incident was a “terror attack”, with the Israeli foreign ministry briefing its diplomats that the attack was against Israel and its relationship with the UAE.

Donald Trump suggested the co-pilot was “perhaps a terrorist or perhaps a whack job”, and told reporters at the White House that he and Netanyahu had spoken at length.

Netanyahu also spoke to the president of the UAE, Sheikh Mohamed bin Zayed Al Nahyan, who agreed to Israel’s involvement in the investigation.

Flydubai said its flights to and from Israel would be suspended while the investigation took place and urged all parties “to refrain from premature speculation while authorities gather the facts”.

The UAE announced on Thursday that it would conduct its own investigation into the incident, which started about two and a half hours after takeoff from Dubai. It said its investigators had begun to look into the attacker’s motive and if he had any links to any “terrorist purpose”.

Passengers said they saw a knife-wielding man – apparently the Omani co-pilot – putting the captain of the plane on the floor, after which the plane began to plummet. The wounded pilot, Smit Machchhar, an Indian national, managed to send out an emergency signal and open the cockpit door, allowing passengers to enter and stop the plane’s descent.

A video shared by the prime minister’s office showed one passenger, Yaniv Hayoun, a plumber, speaking to Netanyahu at length about how the events onboard had played out.

Hayoun told the prime minister he and other passengers heard screaming and felt the air pressure change as the plane dived before they forced their way into the cockpit and found the attacker at the instrument panel. “I grabbed the attacker, put him in a chokehold, and dragged him out first,” Hayoun said during the meeting with Netanyahu after the plane had landed safely and the passengers were flown to Israel.

Machchhar was widely praised for his bravery, with Netanyahu and the Indian prime minister, Narendra Modi, hailing him as a hero. India’s ambassador to the UAE met the wounded captain’s family and briefed them on his recovery, the Indian consulate in the UAE said.

Machchhar was being treated in a hospital in Tabuk, but was in good health and recovering well, according to the Indian embassy in the UAE, which said the ambassador had visited the pilot.

“Captain Smit Machchhar is a HERO,” Modi said, in a post on social media. “In the face of the gravest danger and despite being seriously injured, he showed immense courage and an unwavering resolve to protect the lives of others.”