American officials say an operation to permanently seal the ruptured oil well in the Gulf of Mexico has been delayed until September.
Coastguard Admiral Thad Allen says oil company BP needs to replace key equipment before starting the procedure, which involves pumping cement into the well, the BBC reports.
BP had intended to start the process, known as bottom kill, in mid-August.
The flow of oil was stopped on 15 July, but officials say the bottom kill is needed as a permanent fix.
Meanwhile, new research on the effects of the Deepwater Horizon spill has confirmed the presence of a toxic chemical residue 1km below the water's surface.