A retired military commander who claims to have taken over Papua New Guinea's armed forces has given a seven-day deadline for the government to re-instate former Prime Minister Michael Somare.

Reports say Yaura Sasa and at least a dozen rebel soldiers seized a military barracks in the capital, Port Moresby, on Thursday before taking over the military headquarters and placing the head of the army under house arrest.

At a Thursday news conference in the commander's office, Sasa said he may be forced to take unspecified “necessary action” to “uphold the integrity of the constitution” unless Prime Minister Peter O'Neill steps down and recognizes Mr. Somare.

Sara insists that his takeover is not a “military coup,” instead describing it as “the normal process of replacement of commander by the government.” No violence has been reported.

Sasa wants the country's governor general to implement last month's Supreme Court ruling that found the 76-year-old Mr. Somare was the country's rightful leader. It said he had been illegally removed from office while seeking medical attention outside the country.

Governor General Michael Ogio initially supported the ruling and re-instated Mr. Somare as prime minister, leaving two alternate governments fighting for power. He later changed his mind, saying bad legal advice had led him to re-instate Mr. Somare.

Mr. O'Neill eventually resumed the prime ministership, but Mr. Somare says he remains the country's legitimate leader.

Prime Minister O'Neill is expected to hold a news conference later Thursday to address the matter.

Some observers say that early elections may be the best way to solve the political standoff. Elections are currently scheduled for June 2012.