(CNN) -- More than six weeks after Flight 370 disappeared, Malaysia's prime minister says his government is still not prepared to declare it -- and the 239 people on board -- lost.
"At some point in time I would be, but right now I think I need to take into account the feelings of the next of kin -- and some of them have said publicly that they aren't willing to accept it until they find hard evidence," Najib Razak told CNN's Richard Quest in an exclusive TV interview.
Still, he said, it is "hard to imagine otherwise."
Najib also announced that his government will release a preliminary report next week on the plane's disappearance. The report has already been submitted to the United Nations.
A month ago, Najib announced that, based on satellite data from Inmarsat, investigators had determined the plane's "last position was in the middle of the Indian Ocean, west of Perth. This is a remote location, far from any possible landing sites. It is therefore with deep sadness and regret that I must inform you that, according to this new data, flight MH370 ended in the southern Indian Ocean."
That same day, Malaysia Airlines sent a text to relatives of the passengers saying "we have to assume beyond any reasonable doubt that MH370 has been lost and that none of those onboard survived."
In the interview Thursday with CNN, Najib called it "a bizarre scenario which none of us could have contemplated." How could a plane that was supposed to head toward Beijing end up "half-way toward Antarctica?" he said.
Najib said he repeatedly asked the investigators whether they were sure, "and their answer to me was, 'We are as sure as we can possibly be.'"
Some relatives of those on board and analysts have criticized Malaysia's handling of the investigation, accusing the government of hiding or poorly communicating information.
Asked whether his country had bungled the search, Najib stressed that authorities had faced an "unprecedented" situation that would have been a struggle for any country to handle.
"Some of the things, we did well. We were very focused on searching for the plane. We didn't get our communications right, absolutely right, to begin with. But I think toward the later part, we got our act together," Najib said. "So I'm prepared to say that there are things we did well and things that we didn't do too well."
That's one thing an investigation team will look at, he said.
"We're prepared to look into it," he said, "and we're prepared for this investigation team to do its objective assessment."
The night of the flight's disappearance, a military radar picked up a plane traveling across the Malaysian Peninsula.
Najib said he believes there was someone monitoring the radar, "but the interpretation was done after the event."
It was not known whether the plane was MH370, he said, and no planes were sent up to investigate "because it was deemed not to be hostile." It "behaved like a commercial airline, following a normal flight path," he said.
The vanishing of Flight 370 is "very, very different" from the 1997 crash of a SilkAir flight and the 2009 loss of an Air France flight, Najib added. "This is totally unprecedented." There have been only "pings" and "handshakes" to go by, he said. "That we have analyzed. That is all we have."
CNN's Catherine E. Shoichet contributed to this report.