ANCHORAGE, Alaska (AP) — Environmental groups are renewing a challenge to a 2008 federal petroleum lease sale off Alaska’s northwest shore where Royal Dutch Shell PLC hopes to drill this summer.

The Department of Interior in March concluded that it had sufficiently corrected its flawed environmental analysis preceding the Chukchi Sea sale.

The sale brought in $2.7 billion for the federal government. Shell spent $2.1 billion on high bids and began exploratory drilling in 2012.

Conservation and Alaska Native groups sued to stop the sale. The groups said the former Minerals Management Service had based its environmental review on projected extraction of only 1 billion barrels of oil.

A court-ordered supplemental review assumes an extraction of 4.3 billion barrels.

Earthjustice attorney Erik Grafe says the environmental review remains incomplete.

The controversy has extended to Washington state, where Shell is basing its Arctic oil rigs.