Defense lawyers for a Russian suspect on trial over the downing of flight MH17 called Monday for more investigation of alternative theories including that a Ukrainian fighter jet was to blame.

Prosecutors in the trial in the Netherlands say the Malaysia Airlines plane, which was shot down in 2014 and all 298 people on board were killed, was hit by an air-to-ground missile fired from territory in eastern Ukraine held by pro-Russian separatists.

But lawyers for Oleg Pulatov, the only one of the four suspects on trial to have legal representation, said there should be further inquiries into other theories.

Lawyer Boudewijn van Eijck called for “a different look at the case”.

“The case against our client is very far from ready for assessment in court,” he said.

Another defense lawyer, Sabine ten Doesschate, said they wanted to speak to witnesses who claimed to have heard a Ukrainian fighter jet in the area at the time, and to see more radar data.

Russian officials have previously publicly supported similar theories that a Ukrainian jet downed MH17 in the immediate aftermath of the crash.

Dutch prosecutors last week addressed the fighter jet theory, saying investigators examined radar data that showed no military aircraft in the area at the time.

They also said Russia had backed away from the theory after admitting that radar details appearing to show other planes nearby was in error.

Prosecutors argue the four men on trial were instrumental in bringing a BUK surface-to-air missile system to Ukraine from its original base in Russia, even if they did not pull the trigger.

Pulatov together with fellow Russians Igor Girkin and Sergei Dubinsky and Ukrainian citizen Leonid Kharchenko have been charged by Dutch prosecutors with murder and causing the crash.