SANTIAGO: Scientists testing the remains of Pablo Neruda confirmed the Chilean poet had advanced prostate cancer but it's too early to rule on assertions he was poisoned by the Pinochet dictatorship he strongly opposed, an official said Thursday.

This conclusion was based on X-rays of bone fragments, and the next step is for the judge who ordered the remains exhumed last month to receive the results of toxicology tests from a university in the US state of North Carolina, a judicial source told AFP.

The leftist Nobel prize winning author died 12 days after the 1973 military coup that ousted socialist president Salvador Allende and brought General Augusto Pinochet to power. Neruda was long believed to have died of prostate cancer.

But judicial authorities in 2011 opened an investigation into four-decade-old claims by Neruda's driver that he was actually poisoned by agents of the Pinochet regime.

Neruda won the 1971 Nobel Prize in Literature and is best known for his love poems and his “Canto General”, an epic poem about South America's history and its people.

The Chilean courts gave the go-ahead for the probe after a complaint was filed by the Chilean Communist Party, of which Neruda was a member.

In addition to the driver's accusations, the official complaint quotes witnesses who say Neruda was healthy up until the day before his death and did not exhibit symptoms consistent with advanced cancer.

Driver Manuel Araya says Neruda died after receiving what the driver believed was a suspicious injection at Santiago's Santa Maria Hospital days after the coup, as Neruda prepared to travel to exile in Mexico to lead opposition to Pinochet.

According to Araya, on the afternoon of September 23, 1970, 12 days after Pinochet came to power, Neruda told his wife and the driver that he had been given an injection in the chest that had made him feel bad.

Nearly six hours later, the poet died in the Santiago hospital. Neruda was supposed to have flown to Mexico the next day. The Mexican ambassador to Chile had arranged the flight and a plane was standing by, waiting to take him.

The Chilean judicial system is also investigating the 1982 death of former Chilean president Eduardo Frei (1964-1970), who like Neruda died in the Santa Maria hospital during the military dictatorship following complications from a routine surgery.