THE HAGUE, Netherlands -- It is no longer only grief and mourning sweeping across the Netherlands in the aftermath of the downing of Malaysia Airlines Flight 17. It is now anger.

The Dutch have widely condemned the way the bodies of loved ones have been treated in Ukraine and the fact they have not yet been returned home, four days after Thursday's tragedy.

"No words can describe it," said Silene Fredriksz-Hoogzand, whose son Bryce and his girlfriend Daisy Oehlers died on their way to a vacation in Bali. "Bodies are just lying there for three days in the hot sun. There are people who have this on their conscience. There are families who can never hold the body of a child or a mother."

Prosecutors in the Netherlands said they have begun a criminal investigation, though it remains unclear exactly where any suspects might be brought to justice.

Fredriksz-Hoogzand was among scores of victims' relatives expected at a behind-closed-doors meeting Monday near the central city of Utrecht, where they were to be consoled by King Willem-Alexander, Queen Maxima and Dutch Prime Minister Mark Rutte.

The downing of the Boeing 777 over eastern Ukraine on Thursday killed 298 passengers and crew, including 193 Dutch citizens.

A group of lawmakers hurried back from their summer recess for a meeting Monday with Rutte, who told them that getting the bodies home as soon as possible was his government's top priority. He said a Dutch military transport plane is ready to repatriate the remains, which are now being stored in a refrigerated train in a rebel-held town.

"If the train finally gets going and the bodies get to Ukraine-controlled territory then we would prefer -- and a Hercules is ready at Kharkiv airport -- to get the bodies back to the Netherlands as soon as possible," Rutte said.

One lawmaker, Gert-Jan Segers of the Christian Union, voiced the growing nationwide frustration.

"The Netherlands is grieving," he said. "And angry."

Right-wing lawmaker Louis Bontes urged the government to send special Dutch forces to secure the crash site.

"This messing around with our people can go on no longer," he said. "Our people must be brought home now."

Rutte said he has made it "crystal clear" to Russian President Vladimir Putin that he must use his influence with rebels to ensure unhindered access to the crash scene for international investigators. He says sanctions could be slapped on "those directly or indirectly responsible" for hindering the probe.

"All political, economic and financial options are on the table," he said.

He also said he wants to ensure the perpetrators of the attack are brought to justice.

The Dutch national prosecutor's office has opened an investigation into the downing of the flight, spokesman Wim de Bruin told The Associated Press on Monday.

"We are looking into allegations of murder, war crimes and downing a civilian passenger plane," he said. The charges carry a maximum life sentence if proven in Dutch courts.

De Bruin said one Dutch prosecutor is already in the Ukrainian capital, Kyiv, to work with prosecutors there on the case.

There is no formal day of national mourning yet for the victims, but across the country local commemorations are being held.

A silent march was planned for Monday night in Rotterdam for a couple who ran a popular Chinese restaurant there. In Amsterdam, there were calls spread via social media to gather behind the city's iconic Rijksmuseum to hold a minute's silence.

Fredriksz-Hoogzand said her grief for her son and his girlfriend was still overwhelming.

"When I am in my bed at night, I see my son lying on the ground," she told The Associated Press. "I see Daisy. I see Bryce. I see them in my head. I see it! They have to come home, not only those two. Everybody has to come home."