Hillary Clinton has launched an 11-day tour of Africa by contrasting the US's commitment to democracy with rival powers' focus on exploitation.
Although the US secretary of state did not mention any country by name, her remarks will be widely interpreted as a swipe at China, which eclipsed the US as Africa's biggest trading partner three years ago.
The secretary of state is accompanied by a US business delegation on a seven-nation tour that will include Africa's youngest country, South Sudan, and a private visit to its elder statesman, 94-year-old Nelson Mandela.
During her first stop on Wednesday in Senegal, Clinton told a university audience that the US was committed to "a model of sustainable partnership that adds value, rather than extracts it" from Africa.
Unlike other countries, she continued, "America will stand up for democracy and universal human rights even when it might be easier to look the other way and keep the resources flowing."
Resource-hungry China is often criticised for turning a blind eye to dictatorships and internal repression in its partnerships with African states such as Angola, Ethiopia, Sudan and Zimbabwe. It built the African Union headquarters in Addis Ababa as a gift and has just doubled its credit line to Africa to $20-billion (£12-billion).
Vying for influence
Emilio Viano, a professor at the American University, told Voice of America radio: "One of the major objectives of the visit is to compete with China and try to limit China's influence, business making and political power in Africa."
He added: "The US wants to use this [visit] as a manoeuvre to limit the influence of China. This will not be done openly; it will be done, of course, diplomatically, without naming names, but certainly cautioning African leaders not to strike deals too easily with China."
The Chinese ambassador to South Africa, Xian Xuejun, recently criticised "some western politicians and media [who] tend to make irresponsible remarks on China-Africa relations, attempting to mess up our co-operation."
Senegal is a key US ally in francophone Africa. Clinton praised her host's democratic credentials following an election earlier this year which saw a smooth transition of power from president Abdoulaye Wade to Macky Sall.
She was also expected to discuss security issues with Sall after a coup in neighbouring Mali opened the way for al-Qaeda-linked extremists to seize the country's northern region. This has added to US concerns about militant groups such as Somalia's al-Shebab and Nigeria's Boko Haram.
The US Africa Command, known as Africom, has been pouring resources into training forces throughout West Africa, while Clinton will look to strengthen security ties with Kenya and Uganda in the east.
Jennifer Cooke, the head of the Africa programme at the Centre for Strategic and International Studies in Washington, said: "The security threats are becoming much more visible and in some ways dangerous than they were before.
"There are big global issues on the table and the US does not have the kind of finances available to mount splashy new economic initiatives in Africa."
Clinton's trip will take her to South Sudan on Friday, where she will be the most senior US official to visit since the country declared independence in July last year.
Further stops include Uganda, Kenya, Malawi and South Africa, where Clinton will stop in Mandela's home village of Qunu on Monday for a private meeting with the country's first black president.
She will conclude the trip on August 10 at the funeral of Ghana's late president John Atta Mills, whose sudden death last month led to an orderly succession that underlined the country's stability.
Barack Obama visited Ghana in 2009 but there has been disappointment in some circles that, despite the president's Kenyan heritage, he has not come up with an eye-catching policy initiative in Africa.
Human rights violations
Human Rights Watch urged Clinton to tackle some African leaders over government secrecy and abuses by police and security forces. It highlighted South Africa's Protection of State Information Bill as a potential threat to journalists and whistelblowers.
Daniel Bekele, Human Rights Watch's Africa director, said: "While some of the countries on secretary Clinton's agenda engage in serious human rights violations, others have made notable progress in promoting transparency and accountability. Human rights protection is essential to good governance and development."
Throughout the tour, Clinton is expected to highlight US programmes on development, education and HIV/Aids, as well as US economic interests.
Brooks Spector, a former US diplomat and now political commentator based in South Africa, said: "Clinton is interested in demonstrating some real support for increased trade with Africa – something important as the renewal date for the African Growth and Opportunity Act grows nearer. A key component of this, of course, is that a whole group of American business representatives are also coming at the same time for the kinds of meetings that would help put some heft behind these fine words.
"Naturally, too, if this kind of business interest contributes to giving the Chinese a bit of competition in their efforts to take advantage of African resources and trade opportunities, well then, no one in Washington will be particularly unhappy either." – © Guardian News and Media 2012