The US already buys large amounts of oil from Africa, but both places would benefit from increased trade in an array of other goods, especially farm products, US officials say.

US Secretary of State Condoleezza Rice was opening a brief African visit today with encouragement for African producers attending a trade conference in this western coastal capital.

She will also make two stops in Sudan, where a reconciliation government is emerging from two decades of civil war but where a new conflict is killing and evicting tens of thousands in the Darfur region.

En route to Africa, Rice told reporters she credits a trade program with sub-Saharan countries for a 22% increase in non-oil African exports to the US between 2003 and 2004.

"The theme of this trip is Africans who are empowering themselves through good governance in their trade and through using development assistance wisely," Rice said.

The 5-year-old African Growth and Opportunity Act, or AGOA, allows duty-free exports for more than 6 400 African products to US markets. Examples include baskets, textiles and canned tuna.

Thirty-seven countries have met strict eligibility requirements to participate, but far fewer have seen major increases in US trade so far. Another 11 sub-Saharan countries do not meet the eligibility standards for economic and political reform, commitment to human rights or other measures.

Under the programme, the US imported $26,6bn from Africa in 2004 - all but $3,5bn of it in oil.

"The secretary's point is going to be that a rural society like Africa can do so much more in agriculture," State Department Assistant Secretary for African Affairs Constance Newman said in an interview before the two-day AGOA trade conference.

"Africans should continue trade with the US where they have been successful in the past but they should increase their trade by diversifying," Newman said, "particularly where their strength is, and that would be agriculture."

Nuts, fruits, gourmet coffee and fish are examples of African agricultural products with a ready market in the US, she said.

US Agriculture Secretary Mike Johanns addressed the conference earlier, and US President George W Bush sent a taped message.

First lady Laura Bush just completed a trip to Africa that highlighted humanitarian needs there as well as increased US attention for some of the continent's problems.

Bush announced last month that the US will increase spending to relieve famine and other humanitarian crises in Africa this year, on top of about $1,4bn spent so far this year. The US also spends hundreds of millions annually to fight AIDS in Africa, although critics say it is not nearly enough.

Bush has pledged to double US aid to Africa by 2010.

Rice's two-nation trip to Africa is her first to the continent since taking over the top US diplomatic post in January. She succeeded Colin Powell, the first black to hold the post, and isthe first black woman to do so.