An African government with a reputation for heavy-handedness  is detaining a respected human rights worker on spying charges, drawing condemnation and rebukes from U.S. lawmakers and anti-corruption activists.

Nearly four weeks ago, security forces from the government of Angola stormed the hotel room of Dr. Sarah Wykes, a 41-year-old British activist visiting the country to meet with government and nonprofit officials. 

Wykes' group, Global Witness, has criticized the Angolan government for taking billions of dollars from oil companies while most of its residents live in poverty.

After jailing her for several days, Angolan authorities charged her with espionage. The government has denied Wykes her own lawyer. Though she has been released on bail pending her trial, Wykes is not permitted to leave Angola.

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Global Witness is a non-profit group that has been exposing oil corruption in Angola for years. A recent International Monetary Fund report shows the country has taken in almost $18 billion in oil revenue, but at least $4 billion of it has gone missing. Despite the large profits for the government, more than 70 percent of the country's population lives in poverty.

Global Witness has been lobbying the international community and the U.S. Congress to call for Angola to be more transparent with its oil revenue. 

Diarmid O'Sullivan from the Global Witness office in London says even though the group has had harsh words for the Angolan government, Dr. Wykes arrest was surprising.

"We have been strongly critical of the Angolan government but not recently. Our last major public statement that could be construed as criticizing the government was something like a year ago," he says. "She got the visa from the government, she was planning to meet government officials, and it wasn't her first visit."

The Angolan government will decide this week whether she can return to Britain while awaiting trial. So far, the government hasn't presented any evidence of espionage. 

Fifteen members of Congress have signed letters strongly rebuking the Angolan government's actions. One letter signed by Senators Patrick Leahy, D-Vt., and Barack Obama, D-Ill., urges the government to "personally ensure that Dr. Wykes is not being targeted unfairly and that she is granted permission to return to the United Kingdom at the earliest possible date."

Another letter signed by Representatives Barney Frank, D-Mass., and Tom Lantos, D-Calif., among others, uses even stronger language.  "While the United States values its trading and strategic relationships with Angola and, accordingly, Congress has provided $45 million in military, economic development and humanitarian assistance to Angola in 2007, we are equally committed to ensuring that our allies and partners who benefit from our foreign assistance comply with international standards of human rights."   

O'Sullivan says that while Global Witness appreciates the support from the international community, Dr. Wykes' arrest has had a chilling effect on human rights work around the world.

"There is an enormous network of civil society activists, most of them without the protection of a Western passport, who are struggling day in day out to ensure that their people's basic rights are met, that oil money which belongs to the people is spent for the good of the people," he says,  "and for them to see someone as prominent as Sarah being detained in this way is very serious."

Several calls to the Angolan embassy and consulate for comment were not returned.