It was, in hindsight, not the shrewdest budget cut. A jail in Argentina manned a watchtower with a dummy – a football with a guard's cap – and hoped prisoners would sense constant vigilance.

The synthetic sentinel did not demand a salary, did not grumble about conditions and did not protest its nickname: Wilson, after the volleyball which kept Tom Hanks company in the film Cast Away.

The only flaw in the innovation was that Wilson did not demur when two convicted armed robbers escaped, an oversight owing more to Mr Bean than Prison Break. Walter Pozo, 33, and Cesar Andres, 26, merged into a crowd of departing visitors last Saturday and vanished to freedom in Neuquén, a small city in Argentina's vast Patagonian wilderness.

Rumours of Wilson's existence, and his relaxed approach to guardkeeping, were confirmed today. "For an obvious strategic reason we could not say it before, but now the news is out, I admit that we have a type of mannequin," said Daniel Verges, director of the penitentiary service.

Underfunding meant just two of the jail's 15 towers had guards. Wilson was installed in a third tower on the west wing to boost the sense of scrutiny.

"We've made a dummy out of a football and a prison officer's cap, so that the prisoners see its shadow and think they're being watched," an unnamed prison source told the Río Negro newspaper. "We named him Wilson, like in the film Cast Away, and put him in one of the towers."

An inquiry has been launched amid emergency meetings of security officials. Wilson's penitentiary career is over and he is presumed to have been demoted back to being a football.

Authorities admitted several monitors and surveillance cameras were broken or lacked video cassettes but said cameras in the dummy's sector of the jail were working.

The police chief, Juan Carlos Lepén, said budget cuts meant there was no quick or easy way to fix equipment or properly staff the jail, which is known as Penal Unit 11. "We are trying to resolve this. Our request [for more funds] is with the public administration but we have to wait."

Pozo and Andres were nearing the end of their sentences and kept in a sector with fewer security measures. They reportedly scaled a wire fence and wall, donned overcoats and joined visitors who streamed out of the jail, which is located in an industrial zone, on a wintry Saturday afternoon. The hunt for the fugitives has not gone well so far. A police car crashed into a tree, slightly injuring four officials.