The Melanesian Spearhead Group (MSG) comprising Papua New Guinea, Fiji, Solomon Islands, Vanuatu and New Caledonia’s Front de Liberation Nationale Kanak et Socialiste (FLNKS) will also consider a full membership application by Indonesia.

Outright rejection of the West Papuans by MSG could be a crippling political setback for the freedom movement.

West Papuan groups have been seeking independence from Indonesia since its controversial takeover of the former Dutch colony on the western half of New Guinea in the 1960s.

Hundreds of thousands are estimated to have died in the brutal conflict, with Indonesia accused of human rights abuses.

“It will test our commitment to the basic principles of human rights and the rule-of-law which are embedded in the United Nations charter, which the MSG member countries subscribe to,” Solomon Islands prime minister and MSG host Manasseh Sogavare told leaders at the opening ceremony.

“It is a test of our genuineness to solve a problem between two next-door neighbours, in the interest of regional peace and stability, ultimately it is a test to our claim to civilisation and good corporate citizens of planet Earth.”

For the United Liberation Movement of West Papua (ULMWP), an umbrella group seeking independence from Indonesia, MSG membership would be the climax of years of lobbying efforts to secure a seat on an international forum to push their cause.

“The last 50 years the world ignored our cry for help and justice and peace,” West Papuan leader Benny Wenda told SBS.

“Without West Papua, Melanesia is not free, that’s why we’re confident that when West Papua becomes part of the MSG, it will bring peace itself.”

“We are demanding full membership, but if we are given observer status, we will accept that as a starting point.”

Benny Wenda, Jacob Rumbiak, other exiled West Papuan leaders and supporters have held colourful marches in Honiara over the past week to keep the pressure up.

Fiji and PNG are not expected to support membership for West Papuans, while Vanuatu and New Caledonia’s FLNKS have been long-time backers.

Vanuatu’s position is now uncertain and its leaders will not be at MSG because of a possible no-confidence motion in parliament this week.

Readying for Free West Papua concert in Honiara, Solomon Islands. Via スコット ゲーリー #WP4MSG @westpapuamedia pic.twitter.com/XEN8kM9tsk — Stefan Armbruster (@StefArmbruster) June 20, 2015

The deciding vote could rest with Solomon Islands, the current chair of the MSG.

Last week prime minister Manasseh Sogavare declared he would support observer status for West Papua but not full membership.

At the official opening of the MSG meeting, he went further.

“Let us not forget the dreams of our people to be part of a Melanesian family, the desire of our people to be part of an inclusive MSG, an MSG that will stand for what is right in a world where such values are struggling to survive,” Mr Sogavare said in a powerful speech at the opening ceremony.

The MSG leaders will have to weigh respecting Indonesia’s territorial integrity and maintaining extensive economic relations, especially with PNG and Fiji, against their aim of Melanesian solidarity.

New Caledonia’s FLNKS pro-independence movement full membership of the MSG is the precedent the West Papuans are counting on.

As observers, West Papua would be on an equal footing with Indonesia, which secured the status in 2011, and East Timor (Leste).

MSG leaders will also consider Indonesia’s application to upgrade to full membership, supported by PNG and Fiji, in the form of five Papuan provincial governors who it says are its Melanesian minority population’s true representatives.

MSG leaders have a full meeting agenda including the Melanesian free trade agreement, fisheries, regional policing, disaster relief after Cyclone Pam devastated Vanuatu earlier this year and the "MSG 2038 Prosperity for All" regional plan.

The MSG meeting officially opens on Wednesday and leaders will issue a communique on the outcome for West Papua, Indonesia and other issues by Friday.