The Movement, which was last year granted observer status at the Melanesian Spearhead Group, this week opened an office in the Highlands of Papua province, a building shaped as a circular traditional Melanesian house.
Thousands of Papuans attended the opening which, according to Markus Haluk, a ULMWP official in Papua, serves as an answer to the Indonesian claim that the Movement is only made up of Papuans living outside the region.
The Movement's secretary general Octo Mote said the ULMWP is everywhere in Papua, in all seven of the Papuan customary regions.
Under the Movement, all the major pro-independence Papuan political groups have united to advance their cause and campaign against alleged human rights abuses in their homeland by Indonesian state and security forces.
Following the opening, Mr Mote condemned the move by local Indonesian authorities to subsequently demand the removal of the ULMWP plate in front of the building.
The authorities summoned the Movement's local organisers, concerned about the display of symbols or slogans that could be not in accordance with the principles of the unitary state of Indonesia.
Mr Haluk said they removed the sign but that the Movement's functions will carry on regardless.
Meanwhile, the MSG chairman and Solomon Islands Prime Minister Manasseh Sogavare has welcomed the opening of the office, saying the "ULMWP's presence in West Papua is strategically important."
Another office of the Movement had been the target of Indonesian harassment in July last year, when three ULMWP local representatives for the West Papuan region of Fakfak faced charges regarding their local secretariat.
Indonesian authorities at the time said the ULMWP was considered an illegal organisation due to activities considered rebellion under Indonesian law. The three Movement executives were charged with causing public unrest.
Octo Mote said that it was disappointing that the Indonesian system was still using laws directly inherited from the Dutch colonial era, to enable police and government officials to disrupt ceremonies and meetings, and violate the West Papuans' right to freedom of expression and their right to gather peacefully.
Secretary General Mote said he expected that other ULMWP offices would be opened in other towns of West Papua.