The Senate passed a bill last night extending a program giving poor African countries preferential trade access to the U.S. market.

The bill is identical to legislation approved by the House on June 14 that extends that African Growth and Opportunity Act (AGOA) to 2015. It is expected to proceed swiftly into law with President Bush's signature.

The Senate's action, which came in a voice vote, was hailed by pro-free-trade lawmakers who had feared that the bill would get hung up in the upper chamber because some senators were interested in attaching amendments to a piece of legislation that commanded wide support on its merits.

"This is great news for Africa," said Sen. Charles E. Grassley (R-Iowa), chairman of the Senate Finance Committee, in a prepared statement. He noted that since AGOA was enacted in 2000, "investment in Africa is up, and trade from Africa is up."

The program's chief provision allows Africans to export clothes to the United States duty free. The value of African shipments of garments here has risen from about $600 million in 1999 to about $1.5 billion last year.

The bill's backers warned that if it were delayed, key provisions of the act would expire in September and investors in African factories would pull out of the region for lack of certainty that they would continue to benefit from zero tariffs on their shipments to the United States. The bill passed yesterday extends for three years a provision giving duty-free treatment to African textiles made from yarn and fabrics coming from third countries.

The act covers 37 of the 48 sub-Saharan nations. According to a report submitted by the White House to Congress, imports covered by the program rose to $14 billion last year, a 55 percent increase over the 2002 level.