Papua New Guinea's parliament has elected a new prime minister to replace the ailing independence leader Arthur Somare.

The job has gone to former treasurer Peter O'Neal, who was elected on a vote of 70 to 24 after a number of government legislators joined the opposition in a parliamentary coup.

Somare, 75, has been in Singapore undergoing repeated heart surgeries since April and his family says he is too ill to resume his duties. Acting Prime Minister Sam Abal had been serving in his place.

But several government members joined the opposition Tuesday to declare the post of prime minister vacant. The members then voted to hand the post to Mr. O'Neal.

The decision was a blow to Mr. Abal, who had been expected to serve until new elections are held, likely next year.

However his tenure has been troubled since his adopted adult son was charged with murdering a woman at his residence in June.

Mr. Somare led Papua New Guinea to independence in 1975 and was serving his third term as prime minister when he took a leave of absence in December.

Papua New Guinea is one of Asia's poorest countries, with a majority of its population living on subsistence incomes. But a planned $15 billion liquid natural gas project headed by U.S.-based ExxonMobil is expected to bring increased prosperity.