Spanish energy companies Iberdrola and Endesa have submitted a proposal to review the timeline for phasing out nuclear energy, a spokesperson for the Ministry of Energy told Reuters on Friday.

The proposal was not endorsed by all companies with stakes in Spain's nuclear sector: Naturgy and EDP declined to sign, the spokesperson added.

The proposal ties any extension of nuclear operations to a revision of the fiscal framework. As such, it does not align with the conditions set by Spanish Prime Minister Pedro Sánchez for opening a debate on the matter--namely, that any revision must guarantee supply security, safety, and not impose a burden on taxpayers.

(Reporting by Pietro Lombardi; editing by Inti Landauro and David Latona; Spanish edition by María Bayarri Cárdenas)