The UN’s decolonisation committee will not accept a petition signed by 1.8 million West Papuans calling for independence, saying West Papua’s cause is outside the committee’s mandate.

In New York on Tuesday, the exiled West Papuan leader Benny Wenda presented the petition – banned by the Indonesian government, but smuggled across Papua and reportedly endorsed by 70% of the contested province’s population – to the UN’s decolonisation committee, known as the C24 and responsible for monitoring the progress of former colonies towards independence.

The petition asked the UN to appoint a special representative to investigate human rights abuses in the province and to “put West Papua back on the decolonisation committee agenda and ensure their right to self‐determination … is respected by holding an internationally supervised vote”.

“In the West Papuan people’s petition we hand over the bones of the people of West Papua to the United Nations and the world,” Wenda said of the document. “After decades of suffering, decades of genocide, decades of occupation, we open up the voice of the West Papuan people which lives inside this petition. My people want to be free.”

But on Thursday the chair of the decolonisation committee, Rafael Ramírez, said no petition on West Papua could be accepted because the committee’s mandate extended only to the 17 states identified by the UN as “non-self-governing territories”.

“I am the chair of the C24 and the issue of West Papua is not a matter for the C24. We are just working on the counties that are part of the list of non-self-governing territories. That list is issued by the general assembly.”

“One of the principles of our movement is to defend the sovereignty and the full integrity of the territory of our members. We are not going to do anything against Indonesia as a C24.”

West Papua was previously on the committee’s agenda – when the former Dutch colony was known as Netherlands New Guinea – but it was removed in 1963 when the province was annexed by Indonesia as Irian Jaya.

Ramírez, Venezuela’s representative to the UN, said his office was being “manipulated” for political purposes. Ramírez did not say the petition had not been presented to the committee, only that it was not able to accept it.

“As the chairman of the C24, not any formal document, nothing.”

Asked if he had any communication with Benny Wenda, or the West Papuan independence movement, Ramirez replied: “As the chairman of the C24, that is not possible. We [are] supposed to receive just the petitioners that are issued on the agenda.”

In a statement, Ramírez said that he supported Indonesia’s position that West Papua was an integral part of its territory.

“The special committee on decolonisation has not received nor can receive any request or document related to the situation of West Papua, territory which is an integral part of the Republic of Indonesia.”

Indonesia’s representative to the UN, Dian Triansyah Djani, is a vice-chair of the decolonisation committee.

Spokesman for the Indonesian embassy in Canberra Sade Bimantara said the provinces of Papua and West Papua were sovereign parts of Indonesia: “This fact is indisputable and internationally recognised.

“In 1969 the United Nations reaffirmed Indonesia’s sovereignty over West Papua.”

In response, independence campaigner Wenda, who was granted political asylum in the UK in 2003, told the Guardian that Indonesia’s denial of the petition was further demonstration of its head-in-the-sand attitude to Papuan self-determination.

“The unprecedented petition of 1.8 million signatures of West Papuans has been delivered to the United Nations to remind the UN of the legacy of its failure to supervise a legitimate vote in 1969 and its ongoing duty to complete the decolonisation process.”

Indonesian-controlled Papua and West Papua form the western half of the island of New Guinea. Political control of the region has been contested for more than half a century and Indonesia has consistently been accused of human rights violations and violent suppression of the region’s independence movement.

The people indigenous to the province are Melanesian, ethnically distinct from most of the rest of Indonesia and more closely linked to the people of Papua New Guinea, the Solomon Islands, Vanuatu, Fiji and New Caledonia.

Formerly the Netherlands New Guinea, Papua was retained by the Dutch after Indonesian independence in 1945 but the province was annexed by Jakarta in 1963.

Indonesia formalised its control over West Papua in 1969 when its military hand-picked 1,026 of West Papua’s population and compelled them into voting in favour of Indonesian annexation under a UN-supervised, but undemocratic, process known as the Act of Free Choice.

A 2004 report by the International Human Rights Clinic at Yale Law School said: “Indonesian military leaders began making public threats against Papuan leaders … vowing to shoot them on the spot if they did not vote for Indonesian control.”

Known as Irian Jaya until 2000, it been split into two provinces, Papua and West Papua, since 2003. They have semi-autonomous status.

Many Papuans regard the Indonesian takeover as an illegal annexation and the OPM (Free Papua Movement) has led a low-level insurgency for decades. That insurgency has long been the excuse for significant military involvement in Papua.

With the heightened police and military presence, there have been reports of security force abuses including extrajudicial killings, torture, arbitrary detention, excessive use of force and mistreatment of peaceful protesters. Dozens of Papuans remain behind bars for peaceful demonstration or expressing solidarity with the independence movement.

There is little independent scrutiny of the situation in West Papua, as human rights organisations and journalists are restricted from visiting.