Enbridge Inc, Canada's biggest pipeline operator, plans to accelerate its divestment program by selling assets valued at about $8 billion in 2018, more than twice its initial sale target, according to people familiar with the situation.

Under pressure from both investors and rating agencies, the Calgary, Alberta-based firm wants to ramp up the sale of non-core assets from the previous $3 billion it forecast in November, the people said on condition of anonymity because the process is private.

Enbridge is trying to take advantage of favorable selling conditions to rid itself of unwanted units and pay down its $61.4 billion long-term debt, the people said. Enbridge last year completed a US$28 billion merger with Spectra Energy Corp.

The company, which reports fourth-quarter earnings on Friday, declined to comment.

The shares rose about 1.6 per cent on the news and closed up 0.9 per cent, at $43.23.

As part of a strategic review announced in November, Enbridge said it has identified $10 billion in non-core assets that it could sell over time.

Enbridge is working with an investment bank to sell Canadian and U.S. renewable energy assets worth more than $2 billion, the sources said. It is also looking to offload Canadian midstream assets, largely the result of the Spectra merger, that could fetch as much as $4 billion, the sources said.

Renewable energy assets have drawn interest from investor groups, including infrastructure and private equity funds, in recent years due to a steady return in a low interest rate environment and their increasing prevalence in North America's energy make-up.

Also, Enbridge has hired an investment bank to sell its Midcoast Gas Gathering and Processing business in the United States, the sources said.

Enbridge hopes that selling non-core assets will help speed up debt reduction, enabling it to strengthen its balance sheet and raise its dividend.

In December, Moody's Investors Service downgraded Enbridge's senior unsecured rating to Baa3 from Baa2, partly on concerns about its big debt. Enbridge's November measures were insufficient to improve its financial profile in a timely manner, Moody's said.