April 6 (Reuters) - Midcoast Energy LLC has put its pipeline assets in the East Texas part of the Haynesville Shale up for sale, hoping to fetch as much as $2 billion including debt, people familiar with the matter said on Wednesday.

Energy pipelines have become more valuable since Russia's attack on Ukraine in February drove up oil and gas prices to multi-year highs. Against this backdrop, private equity firms and the energy companies they own are moving forward with plans to divest such assets.

Midcoast Energy, which is owned by private equity firm ArcLight Capital Partners, is working with an investment bank on the sale process, the sources said. The assets being marketed are in the East Texas portion of the Haynesville formation, which also stretches into Louisiana, the sources added.

The sources cautioned that no transaction is certain and asked not to be identified because the matter is confidential.

Neither Midcoast nor ArcLight responded to requests for comment.

Midcoast Energy operates a 3,625-mile (5,834 km) gathering and processing pipeline network that transports natural gas and natural gas liquids, as well as a marketing and logistics business, according to its website.

ArcLight bought Midcoast Energy in 2018 for $1.1 billion from pipeline operator Enbridge Inc. It has since sold some of the original 11,900 miles of pipelines it acquired, including announcing a deal in December to divest assets in Oklahoma to another private equity-backed midstream company.

(Reporting by David French in New York Editing by Matthew Lewis)