Green groups are mounting a last ditch attempt to modify new legislation governing New Zealand's vast exclusive economic zone to protect the marine environment from carte blanche offshore oil, gas and mining exploration.

The Environmental Defence Society (EDS), along with Forest & Bird, WWF-New Zealand and the Ecologic Society, whose director Guy Salmon has been a key figure in government-led environmental policy development, have issued an open letter to Environment Minister Amy Adams.

"We believe that the purpose as worded is certain to lead to the degradation of the marine environment," the letter says.

"It is also likely to lead to extensive litigation and uncertainty for industry looking to invest in offshore exploration."

The Exclusive Economic Zone and Continental Shelf (Environment Effects) Bill passed its second reading in parliament on Wednesday night, and is due to return to the house on July 14, presenting a last opportunity for amendments.

EDS chairman Gary Taylor told BusinessDesk the issue was the latest in a series of environmental policy developments which suggest the government is taking an increasingly pro-business stance since the departure of former environment minister Nick Smith.

"The scales are being tipped on land and in the oceans more towards developmental interests and away from environmental bottom lines," said Mr Taylor, referring also to recommended changes to the Resource Management Act which would enshrine a focus on "balance" between economic and environmental interests.

The RMA favours environmental bottom lines, beyond which development should not occur.

The 11th-hour bid comes as Greenpeace prepares to deliver a 140,000 signature petition to parliament next Tuesday opposing all deep sea oil and gas exploration.