Portuguese parties have reacted differently to the Greek debt crisis, with the government urging Greece to comply with the measures set in its bailout program.

Officials have remained apparently calm while stocks slumped on Tuesday amid fears that Greece will head out of the euro.

Portugal has also applied over the past years for unpopular spending cuts and tax hikes to meet its targets, and is considered the second weakest economy after Greece.

However, as the Portuguese economy shows signs of recovery, the prime minister said Portugal is ready for Greece's default.

"Portugal won't be caught off guard," Portuguese Prime Minister Pedro Passos Coelho said on Monday night.

The government has also called on Greece to comply with the measures set in its bailout program, as the July 5 referendum approaches, claiming that Portugal would be in a similar situation.

"Greece accepting the conditions that were put on the table and which I suppose took into account the demands made by the Greek authorities, would be the best solution for the Economic and Monetary Union," Portuguese President Anibal Cavaco Silva said.

Opposition parties and analysts have been skeptical of Portugal's optimism and its tough demands upon Greece.

"The Portuguese economic structure is very fragile," said economist Ferreira Amaral in a report carried by Portuguese financial daily Diario Economico on Tuesday.

"I agree with the German minister when he proposed Greece exit the euro and suggested a kind of Marshall plan," he said, referring to a U.S.- sponsored European recovery plan enforced after the end of the Second World War.

"I think it would be most indicated for Greece and even for Portugal. If Greece doesn't have the conditions to stay it is not worth forcing the economy to fit into a shoe that isn't its size. Greece, like Portugal, does't fit in."

While sympathy from Europe for Greece is running dry, opposition leaders in Portugal are rallying behind Greek Prime Minister Alexis Tsipras, with several protests taking place in the Portuguese capital to show support for Greece.

Socialist leader Antonio Costa said Greece was a "tragic example of austerity's failure," and criticized the Portuguese government for its lack of solidarity regarding Greece's struggle on Monday.

"It is urgent to replace the confrontation between two radical positions with constructive negotiation," Antonio Costa said in an official statement.

"The national interest, the interest of families and Portuguese companies, is to strengthen the euro zone and the capacity of intervention by the Central Bank."

Portugal's Left Block Party also blamed European governments and the European Commission for failing to reach an agreement with Greece on Monday.

"What is the issue today isn't an agreement about where Greece it is going or not, the money to pay its debt; the issue today is solely if there is space for democracy in Europe, or if Europe is a place of financial dictatorship."

On Tuesday, negotiations between Greece and its creditors collapsed after Greece said it wouldn't pay its IMF loan by the set deadline.

Portugal ended its 78 billion euro (85.5 billion U.S. dollar) bailout last year and has paid back 8.4 billion euros (9.2 billion dollars) to the IMF, while Greece insists on avoiding a payment of 1.5 billion euros (1.6 billion dollars) due Tuesday.