* Russia pushes ahead with trial of dead man
* Lawyer, family say case absurd and politically motivated
* Dispute over Magnitsky case has soured U.S.-Russia ties (Adds quotes, background, details)
By Thomas Grove
MOSCOW, March 4 (Reuters) - A Russian court will start the posthumous trial of a dead anti-corruption lawyer next week after ignoring calls by his family and lawyers to abandon a case they say is absurd and politically motivated.
Sergei Magnitsky's death in custody in 2009, after he had complained repeatedly of being denied medical treatment, has damaged Russia's image and strained ties with the United States.
But Moscow's Tverskoy Court said after a pre-trial hearing on Monday that the trial itself would open on March 11, a court spokeswoman said.
Lawyers say Magnitsky, who was 37 and was accused of tax fraud after investigating similar claims against his accusers, will be the first dead person to go on trial in Russia.
"The trial is indeed absurd," said lawyer Alexander Molokhov after the court rejected his application to defend Magnitsky.
The court had already appointed a legal team to defend Magnitsky after his own lawyers refused to take part in a trial which his relatives say is politically motivated.
Magnitsky's mother, Natalya, has said previously that the case is a farce and her lawyer Nikolai Gorokhov likened the proceedings to "dancing on the grave of a dead man".
The allegations that Magnitsky, who was a lawyer at Hermitage Capital Management investment fund, had committed tax fraud were made shortly after he accused state officials of a $230 million theft by setting up bogus tax refunds.
Critics say the trial is meant to discredit Magnitsky as well as Hermitage owner William Browder, who will be tried in absentia.
President Vladimir Putin has said that Magnitsky, who was 37, died of heart failure but his presidential human rights council has said the lawyer was probably beaten to death. No one has been convicted over Magnitsky's death.
His death has also weighed on ties between Moscow and Washington. U.S. lawmakers passed a bill last year that attempts to punish Russians who were involved in his case and are accused of violating human rights.
Russia, in turn, passed similar measures aimed at punishing Americans suspected of violating human rights.
It also banned U.S. families from adopting Russian children after the death this year of Russian-born Max Shatto, who was adopted by a U.S. family in Texas.
The case against Magnitsky was initially closed after his death in November 2009, but authorities reopened it in 2011 as international criticism over his death - and Russia's apparent reluctance to hold anyone criminally responsible - mounted.
Magnitsky and Browder were charged last year, weeks before the United States adopted the so-called Magnitsky Act which also imposes asset freezes and bars from entry to the United States anyone suspected of a role in his death. (Reporting by Thomas Grove; Editing by Timothy Heritage and Jon Hemming)