A third inquiry into the death of Chilean poet Pablo Neruda 50 years ago could shed new light on whether he was poisoned by political enemies, as alleged by some of his family.

The latest expert report, presented to a court on Wednesday, will be reviewed by judges in closed hearings ahead of a legally binding ruling on the poet's death in 1973 shortly before the Pinochet dictatorship came to power.

Rodolfo Reyes, a Neruda nephew, reiterated this week claims that his uncle - a member of the Communist party and the most important Chilean intellectual of the time - was poisoned.

"(He was) murdered by agents of the state. Is there any doubt?" he told reporters outside the court.

He said he did not have access to the report. Earlier he told Spanish news agency EFE he had seen laboratory documents that supported the poisoning hypothesis.

An international forensics group in 2017 raised doubts as to whether Neruda died of prostate cancer at age 69 and did not rule out foul play.

Previous tests have found no evidence Neruda, winner of the Nobel Prize for literature in 1971, was poisoned.

The report's coordinator, Dr Gloria Ramirez, made no comment on Reyes' speculation about its findings, whose presentation to the court was delayed twice. It has not been made public because of judicial rules governing the inquiry.

Judge Paola Plaza, who is overseeing the case, said there is no deadline on delivering a verdict.

Neruda was a friend and adviser to Chilean socialist President Salvador Allende, who was overthrown in a coup led by Augusto Pinochet in September 1973.