LISBON - Portugal's main opposition Socialists have proposed starting negotiations in "good faith" with the centre-right minority government on next year's budget bill, aiming to avoid further political instability, a party spokesman said.

In the last three months, the new government suffered several setbacks as the Socialists teamed up with far-right Chega to block some of its fiscal proposals, raising doubts about the approval of the budget, which would be the administration's first major survival test.