CARACAS -- Venezuelan President Hugo Ch&aacute;vez moved to jail a prominent opposition figure for the second time in recent weeks, an apparent bid to tighten his grip on power amid a sharp downturn in economic growth.

Venezuela's Hugo Chavez during the opening session of the Arab-South American Summit in Doha, Qatar, on Tuesday. Associated Press

Ra&uacute;l Baduel, a former defense minister-turned-Ch&aacute;vez-critic, was arrested on corruption charges Thursday, according to Mr. Baduel's lawyer, Omar Mora Tosta, and government officials. Mr. Mora Tosta says the charges are unfounded.

The arrest comes after the Venezuelan attorney general on March 19 sought a court order to arrest Manuel Rosales, a former state governor who ran against Mr. Ch&aacute;vez in the 2006 presidential elections, on corruption charges. The arrest warrant hasn't yet been issued. Representatives for Mr. Rosales said he has gone into hiding, and that the allegations against him are unfounded.

Government officials say the actions against Messrs. Baduel and Rosales are the result of legitimate investigations into their financial dealings when they held public office.

Some observers, however, say the moves illustrate how Mr. Ch&aacute;vez is using government institutions to punish political opponents. "All available information suggests that this is selective prosecution motivated by political reasons," says Jos&eacute; Miguel Vivanco, executive director of Human Rights Watch's Americas program. Mr. Vivanco says he was expelled from Venezuela at gunpoint last year after releasing a report critical of Mr. Ch&aacute;vez.

After a decade in office, Mr. Ch&aacute;vez has clinched control of nearly all branches of government. The Venezuelan state oil company, the Supreme Court, the legislature and other institutions are stacked with officials loyal to him, analysts said.

Mr. Ch&aacute;vez has remained popular among his mainly poor supporters, whose living standards have been improved by increased spending on welfare, food subsidies and other programs.

But plunging crude prices have changed the outlook for Mr. Ch&aacute;vez, whose government relies heavily on oil exports to the U.S. for revenue. The sudden economic slowdown has forced Mr. Chavez to curtail spending and raise taxes -- two measures that will hurt the poor and could dent his popularity. Some economists say currency devaluation may be next.

Mr. Ch&aacute;vez appears to be striking at chief opponents before they can use the worsening economy against him, observers said.

A former general, Mr. Baduel was close friend of Mr. Ch&aacute;vez's and played a key role in restoring Mr. Ch&aacute;vez to power after a brief coup in 2002.

Mr. Baduel emerged as a national opposition figure in 2007, when he helped turn public opinion against a referendum to give Mr. Ch&aacute;vez the right to unlimited re-election. He is widely seen as having pressured Mr. Ch&aacute;vez to concede defeat in that referendum. (Mr. Ch&aacute;vez won the right to re-election in a national vote this year.)

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