MADRID (AFP) - Heavy snow continued to fall across much of Spain on Friday (Jan 8), causing chaos on the roads, particularly in the centre of the country, with the capital Madrid seeing its heaviest snowfall in 50 years.

By nightfall, the extreme weather brought by Storm Filomena had left many areas under a deep blanket of white in a rare bout of wintry weather not seen in decades to the Iberian peninsula.

As the snow showed no signs of letting up, Madrid's Barajas airport halted all incoming and outgoing flights.

"For safety reasons, operations have been stopped at #Airport AS #Madrid-#Barajas, until visibility is improved. The work to clear the runways continues in order to resume operations as soon as possible #BorrascaFilomena," it tweeted.

The blizzard also caused havoc on the roads, with nearly 400 affected across Spain and hundreds of vehicles stranded in the snow and ice.

The worst-hit regions were Castilla La Mancha, Valencia and Madrid, with the capital seeing its heaviest snowfall since 1971, Spain's public television said.

Hours of intense snow which was still falling by 2100 GMT (5am Singapore time) cut off the city's two main ringroads, the M30 and the M40, and a red alert was declared in the city centre where police struggled to help people stranded in vehicles.

The transport authority said the snow had disrupted traffic on almost 400 main roads, where in many cases lorries and heavy goods vehicles were unable to pass, while many roads were only passable with snow chains.

On the secondary road network, more than 50 roads were impassable and around 170 roads required chains.

And hundreds of lorry drivers were held up across the country.

The AEMET weather agency described the situation as "exceptional and most likely historic".

Earlier in the day, children in Madrid could be seen hurling snowballs or playing under snow-covered palm trees, while others snapped photos of the rare whiteout which began in earnest the day after Spain celebrated King's Day - or Epiphany.

AEMET had earlier warned another 20cm of snow was expected in Madrid, the high central plains and the nearby mountain ranges, which could rise to 50cm in higher areas.

High-speed trains between Madrid and Valencia were cancelled, the Renfe rail network said.

With many areas struggling to cope with the heavy snowfall, the historic city of Toledo asked the army for help clearing the streets as did Albacete in the southeast, public television said.

Forecasters said the heavy snow would continue until Sunday after which it would subside gradually as Storm Filomena begins moving northeast, although the temperatures would remain exceptionally low.

Before the snowfall began on Thursday morning, temperatures had already plummeted, reaching an unofficial record low of -34.1 degrees Celsius was recorded at a ski station in the central Pyrenees on Wednesday morning.

Storm Filomena has also brought intense rain and high winds to the Canary Islands as well as the southern coast of the peninsula, AEMET said.