Royal Dutch Shell said it was sitting on the sidelines of a Norwegian licensing round, citing tough market conditions and emerging portfolio commitments.

"This was a tough decision reflecting both the challenging current external economic conditions and our continued focus on optimizing our portfolio choices including those afforded by our recent acquisition of BG Group," the Dutch supermajor said in an emailed statement.

Shell last month started production from the third and final phase of operations in the deep waters off the coast of oil-rich Brazil.

The company holds a 50 percent stake and serves as the operator at the deepwater Parque das Canchas development in the Campos Basin. At peak production, the third and final phase of the development should add another 20,000 barrels of oil equivalent per day to a portfolio that's yielded more than 100 million barrels since 2009.

Shell is part of a consortium developing the Libra field off the coast of Brazil, which it acquired in the early 2016 merger with British energy company BG Group, which last year committed a sizable portion of its planned spending on its Brazilian operations.

The Norwegian Ministry of Petroleum in March announced it was auctioning off the rights to explore mature areas in the Norwegian and Barents seas. Many of the 56 blocks up for grabs are situated near areas already producing oil and natural gas.

In announcing the latest licensing round, the Norwegian government said area resources could create value for companies eager to tap into offshore petroleum resources.

Data gathered by Statistics Norway, the government's record-keeping agency, found total investments in oil, gas, manufacturing, mining and electricity for 2015 were around $28 billion, down 9.4 percent year-on-year.