CARACAS (Reuters) - An opponent of Venezuelan President Nicolas Maduro committed suicide in jail, where he had been locked up on charges of fomenting street violence against the socialist government, the Interior Minister said on Friday.

An outraged Venezuelan opposition demanded details surrounding the death of commercial pilot Rodolfo Gonzalez, 64, who was imprisoned in April on accusations of seeking to overthrow the government via massive demonstrations. He had not yet been sentenced.

"Rodolfo Gonzalez took his life by hanging himself," said Interior Minister Gustavo Gonzalez. The state prosecutor's office said it is investigating the death.

The pilot's daughter said he had been anxious about an upcoming transfer to a common Venezuelan jail. Such jails typically are rife with gangs, weapons, drugs and violence.

Reports of a jail transfer are false, said Interior Minister Gonzalez, whom the United States sanctioned earlier this week for alleged human rights violations as head of state intelligence service Sebin.

Opponents say Maduro is cracking down on dissent as his popularity plummets and a severe economic crisis takes a heavy toll on Venezuelans ahead of parliamentary elections this year.

They point to last month's arrest of Caracas Mayor Antonio Ledezma for allegedly seeking to topple the president, as well as the killing of a teenage boy during a protest in the Western city of San Cristobal.

Maduro charges local opposition leaders are in league with the United States to bring him down and get their hands on the OPEC country's oil wealth, an accusation foes decry as a ludicrous smokescreen.

(Reporting by Corina Pons; Writing by Alexandra Ulmer and Ken Wills)