OSLO, May 2 (Reuters) - Equinor has signed a long-term deal with engineering companies to help drive down the cost of developing two offshore oil discoveries that were previously postponed, the Norwegian energy group said on Thursday.

The agreement with the Subsea Integration Alliance, an oilfield services group comprising Subsea7 and OneSubsea, could help revive plans to develop Norway's Wisting field and Canada's Bay du Nord, potentially unlocking around one billion barrels of oil.

"Selecting the supplier at this early stage is a new way of approaching project development for us," Equinor project development head Trond Bokn said in a joint statement with Subsea7.

"We look forward to develop concepts together, in a process with full visibility on profitability, and joint efforts to make these challenging projects sanctionable," he added.

Wisting and Bay du Nord were both discovered more than a decade ago and are believed to contain about 500 million barrels of oil each, Equinor has said.

Both projects face opposition from environmentalists who say the planned production poses a risk to vulnerable eco-systems and that the oil's eventual use will contribute to climate change.

Equinor announced in 2021 plans to invest $8.8 billion to develop the Arctic Wisting discovery which would have made it the world's northernmost oilfield, but postponed the project the following year as cost projections ballooned.

Bay du Nord, located in the Flemish Pass offshore Newfoundland, has received the support of Canada's government, but Equinor last year postponed it by three years, citing soaring costs.

Still, the Norwegian operator has said it hoped to eventually develop the field, and late last year revealed plans for more drilling at Bay du Nord.

Equinor holds a 60% stake in the Canadian discovery while BP owns 40%.

Equinor and Aker BP have 35% stakes each in Wisting, while Norway's Petoro has 20% and Japan's Inpex Idemitsu 10%. (Reporting by Terje Solsvik; Editing by Emelia Sithole-Matarise)