The US Federal Trade Commission (FTC) is postponing its decision on Chevron's proposed $53bn acquisition of Hess until the resolution of an arbitration case involving ExxonMobil, reported Bloomberg, citing sources.
The case, which contests Exxon's claimed right of first refusal over Hess' key assets in Guyana, is expected to conclude no earlier than Q4.
Bloomberg sources indicate that the FTC will wait for the arbitration outcome before announcing its decision on the deal.
The delay is the latest setback for the Chevron-Hess transaction, which has been under scrutiny since its announcement in October last year.
The FTC has been actively requesting additional information on several large oil sector deals throughout the year.
Both Chevron and Hess have said they anticipate completing the FTC review process by Q3.
"We continue to expect to complete the FTC review process during the third quarter," said Hess.
The FTC, which has discretion over the timing of its decisions unless bound by a specific agreement, did not comment on the matter.
Previously, the FTC allowed Exxon's acquisition of Pioneer Natural Resources to proceed, despite allegations of collusion between Pioneer's founder Scott Sheffield and OPEC officials.
Sheffield has denied these accusations.
In March, Exxon accused Chevron of attempting to bypass its right to purchase Hess' 30% stake in Guyana's Stabroek Block, an oilfield containing an estimated 11 billion barrels.
Chevron and Hess have refuted the allegation, arguing that the structure of the deal as a corporate takeover does not trigger Exxon's right of first refusal.
However, the dispute has moved to arbitration under the International Chamber of Commerce, a process that could extend into Q4, with Exxon CEO Darren Woods suggesting it may take even longer.
In May, Hess shareholders narrowly approved the Chevron takeover with a 51% majority vote, despite recommendations from large shareholders and Institutional Shareholder Services to postpone the vote until after the arbitration.
