Papua New Guinea's opposition party is calling for an immediate investigation into allegations of secret deals between a government minister and Asian logging companies totalling millions of dollars.

Our PNG correspondent, Steve Marshall, says it is alleged a government minister has more than $US40 million sitting in a Singapore account from deals struck with Asian companies exporting logs.

PNG's Post Courier newspaper says the secret payments started in 2002 with instalments being made every time a shipment of logs left PNG.

Opposition leader and former prime minister, Sir Mekere Morauta, is calling for a full investigation.

"It is a very clear example of what I have been saying for some time - corruption is systemic and it's institutionalised," he said.

The deputy prime minister, Dr Puka Temu, has demanded the newspaper provide evidence.

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