Pro-Russian separatists continue to receive suspicion from international leaders as they restrict access for investigators to the Malaysian aircraft crash site.

President Obama told the press that international investigation teams have been ready to investigate the site, but pro-Russian separatists are blocking them from accessing it.

“The separatists’ actions begs the question: What are they trying to hide?” he said.

President Obama also called on Russia to take actions to compel the separatists to give access to investigators, adding that if Russia continues to support separatists, “Russia will only further isolate itself and costs will only increase,” according to a Reuters report.

Prime Ministers of Australia and Netherlands also called on Russia to take actions to allow greater access for investigators. Australian Prime Minister Tony Abbott told Reuters that an Australian investigation team had been unable to reach the site, and that although the Ukrainian government has been improving in giving access, the way the site itself is treated is “unacceptable.”

“It’s more like a garden cleanup than a forensic investigation,” he said. 27 or more of those killed in the accident were Australian.

The Netherlands lost 193 people in the accident. Prime Minister Mark Rutte also urged Russia to take action.

“It is clear that Russia must use her influence on the separatists to improve the situation on the ground. If in the coming days access to the disaster area remains inadequate, then all political, economic, and financial options are on the table against those who are directly or indirectly responsible for that,” Rutte said.

Prosecutors from the Netherlands are currently in the process of conducting a criminal investigation into this incident. The Netherlands has the right to prosecute anyone who committed a crime against a Dutch citizen according to the Law of International Crimes, according to the Daily Record.

Despite international suspicion towards Russia and pro-Russian separatists, both have been denying responsibility for the incident.