Adds details from sources on reasons for extension

By Anna Hirtenstein, Marwa Rashad, Dmitry Zhdannikov and Timothy Gardner

WASHINGTON, Feb 26 (Reuters) - The United States has slowed the sale of Russian oil giant Lukoil's international assets to use them as a bargaining chip in the Ukraine peace talks, according to four sources familiar with the discussions.

On Thursday, the U.S. Office of Foreign Assets Control will extend the February 28 deadline to April 1 for deals to be concluded, an OFAC document reviewed by Reuters showed.

U.S., Russian and Ukrainian government officials have not made a breakthrough in talks in Geneva, Abu Dhabi and Miami in recent weeks to negotiate a peace deal in Ukraine. These discussions included the U.S. sanctions on Russia's top oil producer, state-run Rosneft, as well as on second-largest producer Lukoil, according to three sources who were briefed on the meetings.

The next round of talks between the U.S., Russia and Ukraine is planned for March.

OFAC has already extended the deadline three times for potential buyers to negotiate with Lukoil for assets valued at $22 billion since Washington imposed sanctions on the two Russian oil companies in October.

The sanctions forced the sale of Lukoil’s international portfolio, which includes oilfields, refineries and gas stations from Iraq to Finland. The sale has drawn interest from over a dozen bidders ranging from U.S. oil major ExxonMobil XOM.N to the former owner of Pornhub.

OFAC has been handling Lukoil’s asset sale but the process was recently escalated to include senior officials in the White House, Treasury and State Department, with Treasury Secretary Scott Bessent more directly involved, according to three sources.

The White House, the State Department and Treasury did not respond to requests for comment about the extension being related to the peace talks. Lukoil did not respond to requests for comment.

Earlier this month, Ukrainian President Volodymyr Zelenskiy said his intelligence services told him that Russian envoy Kirill Dmitriev proposed an economic deal to the Trump administration valued at $12 trillion. This deal includes Lukoil assets, which may further complicate a sale, according to a person familiar with the matter.

Several companies have signed agreements with Lukoil, including U.S. private equity firm Carlyle Group CG.O, Saudi Arabia’s Midad Energy, and American billionaire Todd Boehly working with investment bank Xtellus Partners and UAE fund Alliance Investment Partners.

A partnership between Chevron CVX.N and Texas-based Quantum Capital Group is also in active talks for the portfolio, but has yet to agree on terms with Lukoil.

(Reporting by Anna Hirtenstein, Marwa Rashad and Dmitry Zhdannikov in London and Timothy Gardner in Washington; Editing by Lisa Shumaker)

((Anna.Hirtenstein@thomsonreuters.com;))