Jan 6 (Reuters) - The U.S. government has launched an investigation into the CIA's destruction of videotapes depicting the harsh interrogations of two terrorism suspects in 2002.

Among the techniques believed to be depicted on the tapes is a form of simulated drowning, or waterboarding. Here are some facts about waterboarding.

* According to Human Rights Watch, waterboarding dates at least to the Spanish Inquisition. The group says that in some versions, prisoners are strapped to a board, their faces covered with cloth or cellophane, and water is poured over their mouths to simulate drowning. In other versions, prisoners are dunked headfirst into water.

* The technique causes reflexive choking, gagging and the feeling of suffocation.

* Waterboarding was used in Central and South America in the 1970s and 1980s, the rights organization says.

* It is believed that the CIA used waterboarding on three "high-value" detainees after the Sept. 11, 2001, attacks, but that it has not used the technique in its detention program since 2003.

* U.S. President George W. Bush insists that the United States does not engage in torture, but has refused to disclose what interrogation methods are used.

Sources: Reuters, Human Rights Watch (Writing by Paul Grant, Washington Editorial Reference Unit; Editing by Xavier Briand)

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