He also extended a state of calamity -- one level below a state of emergency -- in the hardest-hit areas until February 8 as the country braces for more heavy rainfall.

The measure, first imposed on Thursday, gives authorities the power to enforce safety measures and coordinate emergency responses. It was due to expire on Sunday.

"Some areas will face more serious situations, which may even require evacuation," Montenegro said at a news conference following an emergency cabinet meeting, warning that "the ground is saturated".

The national weather agency, IPMA, has placed all of mainland Portugal on alert until Monday for heavy rain accompanied by winds of up to 100 kilometres (60 miles) per hour.

Rainy conditions are expected to continue throughout the week.

Storm Kristin's hurricane-force winds struck central and northern Portugal overnight on Tuesday, causing flooding, landslides and damage to buildings and infrastructure.

As part of the aid package, Montenegro announced a 90-day moratorium on mortgages and other loans for residents in affected areas, and earmarked 400 million euros for urgent road and railway repairs.

"We are mobilising all our resources across the public, social and private sectors to ensure that everything is fully restored as quickly as possible," the prime minister said.

Some 167,000 customers remained without power on Sunday, mainly in central Portugal -- down from just over one million in the immediate aftermath of the storm, according to power company E-Redes.

Two men died on Saturday in separate falls while repairing roofs damaged by Storm Kristin in central Portugal.