“I am fully aware of the current tensions in the debt markets. But let me be very clear that there is a very strong commitment at the highest level to do whatever is necessary to safeguard financial stability,” he said in Lisbon.

“It is extremely important to differentiate across countries.

“The challenges faced by Portugal are not the same as those faced for instance by Greece,” said Rompuy following a meeting with Portuguese Prime Minister Pedro Passos Coelho.

Portugal came under intense pressure last week after credit ratings agency Moody’s slashed its debt rating to junk status, pushing up the price Lisbon has to pay to raise fresh funds and thereby making it even more difficult to stabilise its strained public finances.

It came just as Portugal begins to implement tough austerity measures in return for a 78-billion-euro EU-IMF bailout agreed in April and as the eurozone struggles to craft a new rescue package for Greece.

For Portugal, “the immediate priority is to ensure the full implementation of the measures in the government’s programme,” Rompuy said.

“This is key to restoring investors’ confidence and Portugal.”

Diplomats in Brussels said Tuesday that a meeting of eurozone leaders to discuss the crisis “is under consideration”.

Echoing his earlier stance in Madrid, Rompuy said: “I have not decided on a meeting of the summit of the eurozone, but I do not exclude it.”