Senegal has re-established diplomatic relations with China instead of Taiwan, its foreign ministry has announced.
Senegal is the sixth nation to defect since Mr Chen came to power
The move will give China a minor victory in its long-running dispute with Taiwan, which it claims as part of its territory.
China's Communist government refuses to recognise any country that maintains relations with its island neighbour.
Senegal was one of 26 countries, mainly African and Latin American nations, which maintained relations with Taipei.
Senegal is the sixth country to defect to China since Taiwanese President Chen Shui-bian took office in May 2000.
Liberia, Macedonia, the Commonwealth of Dominica, Vanuatu and Grenada have all recently switched their allegiance to Beijing.
"On Tuesday, the government of Senegal made effective... the important decision to renew diplomatic relations with People's Republic of China," a statement from Senegal's foreign affairs ministry is quoted as saying.
"This historic decision make by President Abdoulaye Wade results from an objective and deep analysis of the global geopolitical situation."
A spokesman at Taiwan's embassy in Senegal, Tsui-Min Hsu, told the Associated Press: "We deeply regret the Senegalese government decision."
Taiwan has suggested in the past that China has been offering millions of dollars worth of aid to impoverished countries to make them switch allegiances to Beijing.
But the Taiwanese government itself has regularly used aid pledges as leverage to win diplomatic recognition.