Washington (AFP) - A World Bank panel has overturned part of a ruling ordering Venezuela to pay $1.4 billion to ExxonMobil in compensation for nationalizing a company project 10 years ago.

In an 85-page ruling, the Washington-based International Centre For Settlement of Investment Disputes (ICSID) agreed with Venezuela's argument appealing the amount of compensation to the US oil giant, and overturned that part of its 2014 decision.

The ICSID ruling was dated Thursday, but released on Friday.

ExxonMobil originally had sought $12 billion in compensation over the loss of what it said it had already invested and what it expected to reap from the Cerro Negro project, which was nationalized in 2007.

In October 2015, the three-member ICSID arbitration panel rejected ExxonMobil's arguments that Venezuela's action represented an illegal expropriation, but awarded the company payment as "just compensation" under an international investment treaty.

The ruling released on Friday cancels the portion of the original award that dealt with compensation for the Cerro Negro project.

"As far as we know, this is the largest annulment in ICSID history," said George Kahale III, who represented Venezuela.

"We were always confident in our legal position and are very pleased that the annulment committee agreed."

ExxonMobil did not immediately respond to AFP requests for comment.

Venezuela's oil ministry celebrated what it said was "an incontrovertible legal triumph."

A founding member of OPEC, Venezuela has the world's largest oil reserves, but its leftist government has been mired in a deepening political and economic crisis.

"We reaffirm to ExxonMobil and other international companies our willingness to continue working together on energy projects... within the framework of national and international law," the ministry said.

Venezuela, which withdrew from ICSID in 2012, still faces a slew of unresolved demands for compensation stemming from a wave of nationalizations during the government of the late president Hugo Chavez.