Malaysia is "deeply concerned" that the site in Ukraine where a Malaysia Airlines plane with 298 people on board was shot down"has not been properly secured", the country's transport minister has said.

Liow Tiong Lai said at a news conference in Kuala Lumpur that "the integrity of the site has been compromised, and there are indications that vital evidence has not been preserved in place".

He called for immediate access for Malaysia's team at the site to retrieve human remains.

"We need the support of the world to ensure that the site is not tampered, that we have access to the site," he said.

Mr Liow, who again defended Malaysia Airlines' flying in Ukrainian airspace, said a Malaysian team arrived in Kiev earlier today, two days after the plane went down.