Reaction:US Secretary of State Condoleezza Rice said today there could be no Middle East peace process if Hamas refused to recognise Israel's right to exist.
"You can't have a peace process if you're not committed to the right of your partner to exist," she told the World Economic Forum in Davos, Switzerland, speaking by videolink.
"And I think you will hear the international community speak clearly on exactly those principles over the next day. There will be some difficult choices before those in whom the Palestinian people are placing their trust."
Hamas, which won the Palestinian election, has a charter that commits it to Israel's eventual destruction, but its armed wing has largely respected a truce negotiated by Mr Abbas and Egypt nearly a year ago.
UN Secretary-General Kofi Annan said today any group wanting to take part in democratic politics should disarm.
Asked if Hamas should renounce violence if it wanted to participate in a Palestinian government, he said: "Any group that wishes to participate in the democratic process should ultimately disarm because to carry weapons and participate in a democratic process and sit in parliament, there is a fundamental contradiction and I'm sure they [Hamas] are thinking about that too."
UN Secretary General Kofi Annan
Speaking in Davos, Mr Annan said he looked forward to working with a duly elected Palestinian government, adding that he had called Palestinian President Mahmoud Abbas to congratulate him on how yesterday's election had been organised.
Mr Annan's spokesman said the secretary-general "views these elections as an important step towards the achievement of a Palestinian state".
The United Nations is a member - along with the United States, the European Union and Russia - in a quartet that proposed a peace "road map" in 2003 laying out steps towards the creation of an independent Palestinian state alongside Israel. The plan has made little progress.
Kofi Annan
British Foreign Secretary Jack Straw also urged Hamas to renounce violence and recognise Israel following its success.
"Hamas has to understand that with democracy goes renunciation of violence," Mr Straw said on a visit to the Turkish capital Ankara.
"It is up to Hamas to choose. We will have to wait and see, the international community will want Hamas to make a proper rejection of violence and to acknowledge that Israel exists," Mr Straw said.
French Prime Minister Dominique de Villepin expressed concern about the Hamas victory.
Asked at a news briefing if France could co-operate with a Palestinian government that included Hamas, Mr de Villepin said: "I don't have the final figures but what is certain is that we are confronted by a situation that leads me to note my concern."
"That's why I think that co-operation with our European partners is essential, and should happen quickly," he added.
Agencies