The amendments to the Environment Act were approved by 73-10 and cover such projects as the $US15 billion PNG LNG project and China Metallurgical Construction Corporation's Ramu nickel-cobalt development.

They also give the director of the environment and conservation office wide-ranging discretion to award certificates to resource developers which grant exemptions from state requirements.

MCC was reported by the Australian to have driven the amendments, which are retrospective and serve to negate an injunction secured by Ramu landowners to stop completion of a pipeline to send slurry waste from the mine out to the sea.

The newspaper quoted George Ireng, who organised a petition opposing the ocean dumping of Ramu tailings, as saying the legislation was a "direct insult, especially to the concerned people of the Rai Coast".

Mount Hagen-based lawyer Tiffany Nonggorr, who represented landowners in obtaining the injunction, has said previously that MCC's plan to dump hot mine tailings annually for 20 years into Astrolabe Bay would interfere with her clients' public and private property rights by causing environmental harm.

This was supported by the court, which found there was unrefuted evidence of possible environmental harm.

The actual mine is located 135 kilometres from the coast and 75km from the provincial capital of Madang, on a plateau 800m above sea level, with material sent to the processing plant near the coast via a slurry pipeline.

The project is expected to produce 31,150t of nickel and 3300t of cobalt per annum in a high-grade concentrate over a 20-year mine life, but resources have the potential to extend this by a further 20-30 years.

Opponents of the new legislation are expected to challenge it in PNG's courts, which are generally considered to be independent of the government with the Supreme Court suspending Treasurer Patrick Pruaitch on Monday over corruption charges.