SANTIAGO (Reuters) - International researchers investigating the death of Chilean poet Pablo Neruda raised doubts on Friday as to whether he died of cancer 44 years ago as previously presumed, and did not rule out foul play.

Neruda, known for his passionate love poems and staunch communist views, died days after a coup in September 1973 that ushered in the brutal dictatorship of Augusto Pinochet.

Neruda's chauffeur claimed Pinochet's agents took advantage of the poet's illness to inject poison into his stomach as he lay in hospital. Neruda's body was exhumed in 2013 and previous tests have found no evidence of poison but are ongoing.

Spanish forensic specialist Aurelio Luna from the University of Murcia told journalists that his team discovered something that could possibly be a laboratory-cultivated bacteria. It will be analyzed, with results expected in six months to a year.

Luna also said that tests indicated that death from prostrate cancer was not likely at the moment when Neruda died.

"From analysis of the data we cannot accept that the poet had been in an imminent situation of death at the moment of entering the hospital," he said.

"We cannot confirm if the nature of Pablo Neruda's death was natural or violent," he added.

Pinochet died in 2006.

Neruda's family and supporters have been divided over whether the case should be closed and his remains returned to his grave near his coastal home of Isla Negra, or whether researchers should continue carrying out tests.

(Reporting by Antonio de la Jara, Writing by Caroline Stauffer, Editing by Rosalba O'Brien)