The Netherlands will tighten its partial COVID lockdown with the early closure of bars, restaurants and shops to curb a spike in cases, Prime Minister Mark Rutte said Friday.

Dozens of protesters demonstrated in The Hague as Rutte unveiled the toughened measures, which come as hospitals warn they are being overwhelmed.

"From Sunday, the whole of the Netherlands is effectively closed between 5pm and 5am," Rutte told a televised press conference.

"We have to be realistic, the daily figures are still too high," he added, referring to infection figures which are running at more than 20,000 a day.

Non-essential shops had previously been allowed to stay open until 6:00 pm, and catering establishments until 8:00 pm.

Patrons must now wear masks and maintain social distancing of 1.5 metres (five feet), meaning that cafes, cinemas, theatres and other venues will have reduced capacity, Rutte said.

Schools will stay open, despite the fact that the largest rise in infections is among children.

Rutte acknowledged that the government had failed to get across the message that people with symptoms need to get tested, since it last tightened the measures two weeks ago.

"I blame myself for that," he said. "We have to do better."

In the protest near government ministries, people rang bells, blew whistles and sirens while many held signs saying "It is not right".

Police vans and riot officers stood guard near the protest, amid tensions after four days of riots last weekend over the government's coronavirus measures.