The United States put Brazil under the spotlight Thursday as it tries to build support within the UN Security Council for tougher sanctions against Iran over its nuclear ambitions.

Brazil -- a current voting member on the 15-strong council but not one of the five permanent veto-wielding members -- has been reluctant to join the US push for sanctions.

The State Department announced that William Burns, the US pointman on talks with world powers on Iran sanctions, will travel to Brasilia on Friday to pave the way for Secretary of State Hillary Clinton's own trip there next Wednesday.

"I wouldn't argue that Iran will be among the major issues we discuss with Brazil," Clinton's spokesman Philip Crowley told reporters when it was suggested Iran would be the main reason for Burns's visit.

While climate change and bilateral issues will also be discussed, "clearly Brazil is an emerging power with growing influence in the region and around the world, and we believe that with that influence comes responsibility," he said.

"And we will be talking to Brazil about the way forward on Iran," he added.

Burns, the undersecretary of state for political affairs, leads US consultations among the P5-plus-1, the club dealing with efforts to halt Iran's contested nuclear program.

The group is made up of the five permanent veto-wielding members of the UN Security Council -- the United States, Russia, China, Britain and France -- plus Germany.

"I am certain that undersecretary Burns will bring them up to date on the P5-plus-1 process," as will Clinton, Crowley said.

During her five-country tour of Central and Latin America, Clinton will meet Wednesday with Brazil's President Luiz Inacio Lula da Silva and Foreign Minister Celso Amorim in Brasilia.

Lula at a regional summit in Mexico on Tuesday warned that the global community, in its quest for peace, should avoid isolating Iran over its controversial nuclear program.

"Peace in the world does not mean isolating someone," said Lula, whose country has its own nuclear energy program.

Brazil's Senate foreign relations committee on Thursday called Amorim to testify about the country's policy towards Iran.

Clinton's tour follows one to the oil-rich Gulf less than two weeks ago when she asked Saudi Arabia, the biggest oil exporter to China, to use its influence to persuade Beijing to join the drive for sanctions against Iran.

A senior European diplomat in Washington said Thursday that the United States, Britain, France and Germany agree to a set of sanctions targeting Iran's alleged proliferation efforts, nuclear technology and the Revolutionary Guards.

The Guards, which Clinton this month charged are supplanting the clerical and political leadership in Tehran, run Iran's nuclear and missile programs. They have also lead the crackdown against anti-government protesters.

The European diplomat hailed "positive noises" from Russia for such sanctions.

But he said it is possible that China might abstain in a sanctions vote, along with Brazil, Turkey and Lebanon. "It could well be we get four abstentions," the diplomat told reporters on condition of anonymity.

Crowley, citing the Revolutionary Guards, said sanctions are intended to "pressure the government while protecting the people."