CHICAGO (AFP) - Relatives of MH17 crash victims have filed a nearly US$900 million (S$1.2 billion) suit against a one-time leader of Ukranian insurgents over the shooting down of the jet over the rebel-held east of the country last year.

A writ filed in Chicago on Wednesday claimed that Igor Strelkov, a Russian also known as Igor Girkin, was acting with the "actual or apparent" authority of President Vladimir Putin's government when the Malaysia Airlines jet was blown out of the sky, killing all 298 people on board.

Relatives of 17 victims are being represented by a US-based firm specialising in aviation litigation, which is claiming at least US$50 million for each of the plaintiffs' loved ones.

Strelkov's wife Miroslava, who also acts as his spokeswoman, said the former rebel - a self-professed Russian former intelligence agent who spearheaded the insurgency until last August and is now based in Russia - would not comment.

"What does he have to do with this anyway," she said on Russian radio.

In an online comment later on Thursday, the mustachioed rebel said he did not have US$900 million and derided the families of the victims who include British nationals.

"It is deeply symptomatic that British people 'valued' the lives of their relatives in monetary terms," he wrote.

"All their morality and all their 'universal human values' have a monetary equivalent. That is what I've been fighting my whole life and am ready to fight in the future."

TERRIBLE LOSSES

Attorney Floyd Wisner told AFP that the lawsuit was not about money.

"It has everything to do with finding the answers to this criminal event and bringing the perpetrators to justice," he said in an e-mailed statement.

"Our clients do not want their terrible losses to be forgotten.

"We believe Mr Girkin has important information about these acts and we challenge him to appear and respond to this lawsuit."

The court papers say that "Flight 17 flew over the airspace of the area in which the aforesaid rebel army was waging its war activities and the rebel army under the command responsibility of defendant Girkin shot down the subject Boeing 777-200 aircraft."

"Defendant Girkin ordered, aided and/or abetted this action and/or conspired with those persons who fired the missile or missiles."

The lawsuit was filed almost a year to the day when the passenger jet travelling between Amsterdam and Kuala Lumpur went down on July 17 during some of the worst fighting between government forces and pro-Russian separatists.

All 298 passengers and crew on board - the majority of them Dutch - died.

Ukraine and the West have accused the separatists of using a surface-to-air missile supplied by Moscow to down the Boeing.

Russia has denied the claim and suggested that a Ukrainian missile may have hit it.

In a bid to counter raging accusations that he was personally guilty, an ashen-faced Putin recorded an unprecedented nighttime video address soon after the tragedy, urging the West and Kiev not to exploit the disaster for political gains.

Malaysia earlier this month formally asked the United Nations to establish an international tribunal that it said would guarantee an independent trial for those behind the MH17 disaster.

Putin, speaking to Dutch Prime Minister Mark Rutte Thursday, said that establishing such a court would be both premature and counterproductive.