The Spanish-led consortium working on a project to widen the Panama Canal has said that work at the site has been halted over a disagreement on cost overruns.
The construction group says it is owed $1.6bn (£1bn).
The Panama Canal Authority (ACP) said the demand amounted to blackmail.
The new lock, which was due to be completed next year, would allow the passage of larger cargo ships in one of the world's busiest maritime routes.
Failed talks
On Wednesday, the consortium - officially known as Grupo Unido por el Canal (GUPC) - denied that work at construction work had been suspended.
It said 10,000 jobs were at risk if there was a stoppage.
But in a statement on Friday, the group blamed the Canal Authority for failing to extend a negotiation protocol.
In the protocol, the building companies agreed to carry on negotiating without threatening to suspend the work, while Panama promised not to cancel the contract signed by both parties
"While awaiting an agreement to enable the finalisation of construction, work has been suspended on the project," announced the consortium in a statement.