A major power cut across large parts of Spain and Portugal has resulted in dozens of flights being cancelled as well as disruption to rail and road networks.

Some 96 departing flights from Portuguese airports have been grounded so far, with the country's capital city airport in Lisbon worst affected.

A total of 45 flights have been called off from Spain, with Barcelona and Madrid airports impacted the most.

The cause of the outage has not yet been established and, while some power supplies have been restored, the head of Spain's electricity grid said on Monday afternoon restoring all power could take "between six and ten hours".

The outage began soon after midday Spanish time and cities across the country have been impacted, although the popular tourist destinations of the Balearic and Canary Islands have not been as badly affected.

The blackouts have led to public transport being disrupted, with trains being cancelled. Traffic lights being affected led to the mayor of Madrid to ask residents to keep the roads clear as tunnels of certain highways were closed.

According to aviation analytics firm Cirium, Lisbon airport had the most (29.6%) departure cancellations in Portugal by Monday evening. A total of nine flights from the UK to Portugal were also grounded.

The BBC understands that Lisbon airport has limited its flow rates - effectively not allowing planes to arrive or there are delays getting planes in, which then knocks on to the tight system of airport operations, where planes normally arrive and leave in strict timeframes.

Barcelona and Madrid made up the majority of cancellations from Spanish airports, but zero flights from the UK to Spain have been scrapped, according to Cirium.

David Gleave, an aviation investigator, told the BBC any interruption to power supplies at airports would not affect air traffic control as "a battery will kick in a maximum of a second later, so airplanes are safe".

"From then on, a diesel-powered generator will keep power running so air traffic control can function," he added.

He said it was likely airports in Spain and Portugal have independent power supplies, "which will see big diesel generators which fire off when it senses no power from its usual grid supply".

Enaire, Spain's air navigation organisation, confirmed that a back-up generator had meant air traffic management operations were continuing to run from its five control centres.

"Appropriate regulations are being implemented to ensure the complete safety of operations," it added.

Iberia, Spain's national airline confirmed on X that despite the widespread power outage its systems were "operating at 100%".

"However, given the difficulties at several airports, we are offering all passengers with flights scheduled for today the option to reschedule their trip," it said.

While some flights are running as normal, the issues impacted the roads and public transport is likely to be a problem for travellers trying to get to airports.

Spain's Transport Minister Oscar Puente said it was not likely that medium and long-distance trains would resume normal service on Monday.

He said the plan was to resume shorter-distance commuter services as soon as electricity supplies had been restored. Work is also under way to rescue people trapped on stranded services.