Akhir 19, 1432 H/March 24, 2011, SPA -- Market pressure on Portuguese debt mounted Thursday in the wake of Prime Minister Jose Socrates' resignation, raising the likelihood of the country seeking an international bailout, according to dpa. The yield for Portuguese five-year bonds soared to 8.4 per cent, the highest level since Portugal adopted the euro in 1999. Antonio de Almeida Santos, president of Socrates' Socialist Party, said President Anibal Cavaco Silva now had few alternatives other than to call early elections. It was likely that Portugal would seek external financial aid, Almeida Santos said. Portugal would be the third eurozone country after Greece and Ireland to be bailed out by the European Union and the International Monetary Fund. Socrates presented his resignation to Cavaco Silva late Wednesday after parliament rejected his latest austerity package. The premier was nevertheless due to attend a key EU summit on restoring investor confidence in the eurozone on Thursday and Friday. Socrates' minority Socialist government had been trying to cut the budget deficit to 4.6 per cent this year from 7.3 per cent in 2010 in an attempt to ward off a bailout. Cavaco Silva was due to start talks with party leaders Friday in an attempt to find a solution to the political crisis. He was widely expected to maintain Socrates' government in office as a transitional government until elections were held in May or June. The president could also seek the formation of a coalition government, but that was deemed unlikely because of the bad relations between the Socialists and the opposition. Socrates on Wednesday accused the opposition of having "blocked the entire country" by rejecting his austerity package, and warned that Portugal would have to adopt "much tougher measures" if Lisbon sought a bailout. The austerity package was rejected by all the opposition parties, including the conservative Social Democratic Party (PSD), which is tipped to win the eventual elections. Socrates meanwhile faced more strikes against his austerity policies, with the Lisbon underground coming to an almost complete standstill, according to trade union sources. There would be no underground trains in the morning hours, the sources said.