Yesterday's Nice Treaty referendum result was greeted with shock in Brussels and with dismay in the capitals of candidate countries seeking membership of the EU.
Mr Romano Prodi, the Commission President, and Mr Goran Persson, the Prime Minister of Sweden, which holds the EU's rotating presidency, issued a joint statement expressing their disappointment.
"We are very disappointed at the result of the referendum in Ireland. None the less we fully respect the outcome of this democratic process," they said.
The two leaders acknowledged that Ireland was a strong supporter of enlarging the EU and expressed the hope that the Government would make every effort to secure ratification before the agreed deadline of the end of 2002.
But they made clear there could be no renegotiation of the "substance" of the Nice Treaty. And they affirmed the EU's determination to press ahead with negotiations with 12 candidate countries.
Ireland's EU Commissioner, Mr David Byrne, called for a close examination of the reasons behind yesterday's result.
"I believe there is considerable confusion about the Nice Treaty, what it means and more particularly what its implications are. This is not unique to Ireland," he said.
He called for greater efforts to involve the public in the debate about Europe's future and expressed confidence that Ireland would eventually endorse the treaty.
The Commission's chief spokesman, Mr Jonathan Faull, declined to rule out a renegotiation of the treaty.
And he acknowledged that the agreement's complexity could have played a role in its rejection.
"Nobody will pretend the Treaty of Nice is the simplest, most user-friendly text they have ever read, but it marks a step forward in the direction we want towards enlargement and the debate on the future of Europe," he said.
The EU Enlargement Commissioner, Mr Guenter Verheugen, said the referendum result could not block the enlargement process.
But Hungary's Foreign Minister, Mr Janos Martonyi, warned that it could affect the mood of accession negotiations.
"I don't think that it has the potential to delay entry, but the atmosphere would definitely change," he said.
The head of the European affairs section at the Czech foreign ministry, Mr Petr Kubernat, said that the result should not be interpreted as a rejection of enlargement. But he stressed that the Nice Treaty removed the "brake" to the process.
In neighbouring Slovakia, the reaction was gloomier.
"The Irish No is bad news for Europe," a foreign ministry spokesman said.
A spokesman for the Cypriot government said that the EU must ensure the referendum result did not lead to any slowdown in enlargement negotiations.
"Definitely, this is not a good message. It creates the necessity of the European Union, of member-states and candidate states to find ways to overcome difficulties so that the whole process will not be delayed," he said.
