In the BBC interview, Mr. Buckles said he was “pretty sure” the guards already deployed could speak English well, “but I cannot say categorically as I sit here today.”

On Thursday, when the government acknowledged the extent of the bungling and announced that it would be adding 3,500 additional troops to the 13,500 troops already committed to security duties at the Games, it offered assurances that the security for the 17 days of competition would not be compromised.

Theresa May, the home secretary, who is one of the most powerful figures in Prime Minister David Cameron’s government, laid the blame on G4S and Olympic organizers who negotiated the G4S contract and said that the extent of the security mismanagement had only “crystallized” 24 hours before she reported it to the House of Commons.

Lawmakers have said they will summon G4S executives and others involved in the security planning to testify about the imbroglio when Parliament reconvenes after its summer break, weeks after the Olympic Games have ended. In any case, the political fallout for the Cameron government is likely to be mitigated by the fact that much of the planning for the Games — or lack of it, as it appears now — took place in the five years after they were awarded to London in 2005, when the opposition Labour Party was in power.

But that has not prevented some dire conclusions from being reached. The Times of London, in an editorial in Friday’s editions, held out the hope that the worst prognostications “will melt away under the impending, all-consuming blowtorch of a city” — London — “having the time of its life.” But it said failures in security planning and other problems already pointed to a debacle.

It cited emergency repair work on the main highway connecting Heathrow Airport to central London — part of a route to the main Olympic site — that has closed a six-mile stretch of roadway, with no certainty when the work will be completed. Major weaknesses have been found in the steel supports for a flyover along the roadway. “Let’s no longer beat about the bush,” The Times said. “This summer’s Olympic Games are going to be a catalog of disasters. Not everything that can go wrong will go wrong. Only lots of it.”

In the dispute over security planning, the picture that has emerged has been one of haphazard planning going back several years. The original contract with G4S provided for only 2,000 guards, and a relatively small military contingent.