A nurses' strike in Portugal which brought non-essential operations to a standstill for nearly three weeks over demands for higher pay ended on Wednesday after a union called it off, the government said.

Operating theatres reopened fully in 10 hospitals that had delayed thousands of procedures, a health ministry spokeswoman told AFP.

The Portuguese Nursing Association (ASPE) - one of two unions which organised the action - buckled under government threats that the nurses would not be paid because their absence was "illicit" and "unjustified".

Lucia Leite, president of the ASPE union, called for the "immediate" suspension of the strike but vowed that the nurses would not "give up the fight".

The workers want higher wages, more overtime pay and the end to a freeze on promotions imposed during the crippling financial crisis.

More than 3,800 operations were delayed between February 1 and 14, the health ministry said.

The strike had been called for the entire month of February.

Meanwhile however, the other union - the Democratic Union for Portuguese Nurses (Sindepor) - refused to go back to work, with its president launching a hunger strike outside the presidential palace in Lisbon.

"We will continue this fight until the end," Carlos Ramalho told AFP.

"If nurses are forced back to work, they will of course respect orders, but they will sign a declaration saying they have been forced to work under duress and under threats," he said.