One of the two newly-appointed figures to the European Union's top jobs has hit back at criticism that she does not have enough experience for the post.
Baroness Catherine Ashton told the BBC she was "the best person for the job" after her surprise choice as the EU's new foreign affairs chief.
Baroness Ashton was speaking after the two appointments of little-known figures drew a mixed response.
Belgian PM Herman van Rompuy was named President of the European Council.
The US welcomed the announcement, saying it would make Europe a stronger partner.
However, the BBC's Jonny Dymond in Brussels says there has been some dismay at the choice of two candidates with a low international profile.
Some of those applauding the appointments are Eurosceptics - they can live with a relatively low-profile 'chairman'
British newspapers said the choices would not help the EU to achieve a greater global impact and questioned whether Baroness Ashton would carry much weight in her new role, which had been dubbed the "EU's foreign minister".
But Lady Ashton, the former EU trade commissioner, said European leaders were "very comfortable" with her appointment.
"Over the next few months and years I aim to show I am the best person for this job," she said. "I think for quite a few people, they would say I am the best for the job and I was chosen because I am."
'Discreet leadership'
The post of president has become a much less important one than originally envisaged, our correspondent adds.
German Chancellor Angela Merkel said Mr Van Rompuy would bring consensus and political competence to the presidency.
However, Turkish member of parliament Onur Oymen said he was concerned about what Mr Van Rompuy's presidency could mean for Turkey's aspirations to join the EU.
He told the BBC's World Today that Mr Van Rompuy had "said a few years ago he was totally against Turkish membership because of religious and cultural reasons".
"We are not very optimistic about the future of our relations during his presidency," Mr Oymen said.
Mr Van Rompuy said he would be "discreet" in his new job, adding that he sees climate change and Europe's high unemployment as key concerns in the years ahead.
Baroness Ashton and Mr Van Rompuy were chosen unanimously by the 27 EU leaders at a summit in Brussels.
Both have been seen as consensual politicians with limited foreign policy experience.
US President Barack Obama said the appointments would "strengthen the EU and enable it to be an even stronger partner to the United States".
He said the US had "no stronger partner than Europe in advancing security and prosperity around the world".
'Milestone for Europe'
US Secretary of State Hillary Clinton said the appointments were a "milestone for Europe and for its role in the world".
Herman van Rompuy: Every country should emerge victorious from negotiations
She said she was looking forward to working closely with Mr Van Rompuy and Baroness Ashton on issues of mutual concern, including the Iranian nuclear debate, achieving stability in Afghanistan and promoting a peace agreement in the Middle East.
The President of the EU Commission, Jose Manuel Barroso, also praised the appointments, saying it would be "impossible to find a better choice than those personalities for the European Union leadership".
Mrs Merkel said of Mr Van Rompuy: "We got a candidate who brings consensus and whose political competence have long been tested and tried throughout his political career."
French President Nicolas Sarkozy said it had been "a very wise decision" to choose a candidate from "an important country but not one of the most important countries, so that no-one will feel excluded" from EU debate.
Addressing the summit after his appointment, Mr Van Rompuy said the EU was "living through exceptionally difficult times".
THE PRESIDENT'S ROLE
Chosen by leaders of 27 member states
Two-and-a-half-year term
Can be re-elected once
Chairs EU summits
Drives forward the work of EU Council of Ministers
He said the financial and climate crises "threaten our very survival" but that the problems "can be overcome by a joint effort between our countries".
Baroness Ashton said she would pursue a policy of "quiet diplomacy" in her role as High Representative for Foreign Affairs.
She said she had the relevant skills for the job and that she had developed strong relationships during her time as EU Trade Commissioner.
British Prime Minister Gordon Brown denied accusations that Baroness Ashton lacked sufficient clout, and said her appointment was "a sign of the regard that people have for Britain".
The two new posts were created by the Lisbon Treaty, which will come into force on 1 December.
The EU president will chair regular meetings of the European Council at which decisions are taken about the political position of the bloc.
However, correspondents say the High Representative for Foreign Affairs and Security Policy, as the post is officially known, could have an even more powerful role.
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