Thirty-eight-year-old Munir died on 7 September aboard a flight from Jakarta to Amsterdam.
An autopsy performed in the Netherlands concluded lethal doses of arsenic found in Munir's body caused his death.
The results were reported to the Indonesian foreign ministry, NRC Handelsblad newspaper reported on Thursday. By late Friday afternoon his family had yet to receive a copy of the autopsy.
"As his wife, I should be the first person to receive my husband's autopsy results, not the government," his widow Suciwati Munir said on Friday at a press conference at the offices of the Commission for the Disappeared and Victims of Violence in Jakarta.
British human-rights organisation Tapol, which worked closely with Munir and others attempting to shed light on the excesses of Indonesia's security services, called for an immediate investigation.
Widow Suciwati said she ought to
have got the autopsy report first
Tapol, in a statement, called on the Indonesian government "to order a thorough investigation to discover the perpetrator or perpetrators of this wicked crime and for the attorney-general, Abdurrahman Saleh, to bring criminal charges against the suspects without delay".
The Dutch government also called on Jakarta to pursue the case. "The Dutch Foreign Office is of the opinion that a further criminal investigation is justified and conveyed this opinion to the government in Jakarta," an official release said.
A foreign ministry spokesman could not be reached to clarify why the autopsy had not been provided to the family. Earlier he told the online news service detik.com that it would not be released until a police investigation had been completed.
Indonesian authorities said a police team would be sent to the Hague to meet directly with members of the Dutch Forensic Institute who performed the autopsy.
Munir's inquiry blamed security
forces for student deaths in 1998
"The results that we received shows that the body of the late Munir contains arsenic or metals which exceed normal levels, although we cannot determine when he consumed them," Chief of Detectives Suyitno Landung said. "We also cannot determine in what form the arsenic was consumed - whether it was carried in water or other things."
Munir was a noted critic of former president Suharto, gaining prominence but also powerful enemies with his investigations into the activities of the Indonesian military.
He led the independent inquiry that concluded security forces were responsible for the shooting of pro-democracy student activists in Jakarta in 1998 and the disappearance of dozens of activists.
In 2000, Munir helped expose human rights abuses by Indonesia's powerful military and their militia proxies in East Timor, and was a vocal opponent of Jakarta's decision to declare a state of emergency in the restive northern province of Aceh.
Indonesian military's East Timor
abuses were exposed by Munir
He became violently ill shortly after the Garuda Airlines flight left Singapore, vomiting and complaining of stomach cramps.
A doctor on board attempted to treat his symptoms but Munir, a married father of three, died a short time before the plane arrived in Amsterdam.
He had suffered for many years the effects of Hepatitis C and had been ill in the months prior to his trip. Initial reports suggested he had suffered a heart attack.