Transocean Ltd. and the Justice Department have discussed a $1.5 billion settlement that would resolve federal claims over the company’s role in the 2010 rig explosion that led to the nation’s worst offshore oil spill.

But Switzerland-based Transocean Ltd. said in a regulatory filing Monday that several issues, including the possible time period for payment, must be resolved before a deal can be completed.

A Justice Department spokesman declined to comment.

Transocean owned the Deepwater Horizon drilling rig, where 11 workers died in an April 2010 explosion triggered by a blowout of BP’s Macondo well.

Transocean also says it rejected settlement offers earlier this year from BP and a group of private attorneys for Gulf Coast residents and businesses.