LONDON, England, July 16 – Shares in G4S shares plunged on Monday after the British security group said that its failure to provide enough guards at the London Olympics would cost it up to £50 million ($78 million, 64 million euros).

In early morning deals, the company’s share price dived by almost 10 percent in value. It later stood at 259.2 pence, down 7.0 percent from Friday’s closing level.

London’s FTSE 100 index of top companies, on which G4S is listed, was 0.05 percent lower at 5,663.06 points.

G4S chief executive Nick Buckles was forced to apologise on Saturday for blunders over recruitment which have forced the British government to deploy extra troops to guard the London Olympics at the last minute.

Buckles said that he was “very sorry” that 3,500 troops have had to be drafted in just two weeks before the Games, after the company admitted it could not provide the total 10,000 guards it said it would.

Speaking publicly for the first time since details of the fiasco emerged last Wednesday, Buckles confirmed that G4S faces losses of between £35-50 million in the current financial year, over the blunder.

“We accept that we underestimated the task of supplying staff for the Olympics. We deeply regret that,” Buckles told BBC radio on Saturday.

He admitted that he had realised only “eight or nine days ago” that there would be a shortfall.

“It’s only when you get closer and closer to the Games that you realise that the number isn’t as high as you expect,” he said.