New Delhi, Nov. 11 -- Deadly rioting that broke out at a prison in Ecuador where inmates were set to be transferred to a new maximum-security facility has left at least 31 inmates killed and 30 others injured, prisons officials said Monday.

Authorities gave few details of the violence Sunday at the prison in Machala in southwest Ecuador, but the country's prison oversight agency said that 27 inmates died of asphyxiation and four others of unspecified causes. Authorities initially reported regaining control of the facility after only four deaths, but later reported the additional deaths following what they said was a separate flare-up of rioting.

The agency, which said one police officer was injured, did not respond to a request for addi...