US Secretary of State Hillary Rodham Clinton has embarked on six-nation trip to repair relations with Latin America.

US-Latin American relations were strained by last year's agreement with Colombia that gives the US a military presence in the region despite protests from neighbouring countries.

The tour is Clinton's first to Latin America since the Obama administration took office a year ago and comes with the promise of a more attentive and cooperative US approach to the region.

But rebuilding bridges will not be easy. Many countries are enraged by the US-Colombian military accord and discontent was fueled after the US recognized the general elections organised by the coup leaders in Honduras.

Brazil, as one strongly opposed to the coup in Honduras and the subsequent election, criticized the US acceptance of the election outcome.

In turn, closer Brazil-Iran ties have worried the United States, in particular Brazil's insistance on dialogue rather than sanctions to solve the Iranian nuclear issue.

Argentina is also disappointed with the US approach toward Honduras and was then further put out by what it regarded as a snub on the current tour.

Argentina is also still upset about a senior US State Department official's criticism of the country's judicial security.

But Argentine President Cristina Fernandez de Kirchner has requested a US mediation between her country and Britain over the disputed Southern Atlantic islands where Britain has started drilling for oil.

Clinton's visit started at a time when the Rio Group had just enlarged its membership while leaving the United States out in the cold.

The move was seen as a challenge to American influence in the region.

Observers say Clinton may aspire to ease relations with major South American countries through her current visit and to persuade Brazil to second the US move against Iran's nuclear program.

But it won't be easy to achieve these two goals with one trip, according to Julia E. Sweig, director for Latin American Studies at the US Council on Foreign Relations.

Sweig, also the Nelson and David Rockefeller senior fellow for Latin American studies, says the US image in Latin America has been undermined by a whole series of divergences on foreign policy issues and the visit alone will not solve the differences.