London ( CNN ) -- The chairman of the London 2012 organizing group Friday rejected concerns over security staffing ahead of the Olympic Games , which start in two weeks . Sebastian Coe told reporters he was `` extraordinarily impressed with '' private contractor G4S so far . His comments follow the announcement by the British government Thursday that an extra 3,500 military personnel are needed to cover a shortfall in recruitment by G4S . Coe said he was happy with the security staff on site and that while G4S has `` challenges , '' it will get there . No one can underestimate the task ahead , he said . Coe would not comment on the `` robust '' contract the organizing committee ( LOCOG ) has with G4S . Home Secretary Theresa May addressed the issue Thursday . `` There is no question of Olympic security being compromised , '' May said . Going to the Games , or watching from home ? Send us your pictures and videos . She said it became clear Wednesday that G4S was not able to provide all the security staff it had promised to the organizers of the London Olympic Games . The government 's decision to bring in additional troops , on top of the 13,500 already agreed , was the appropriate response to the shortfall in G4S staff , she said . The deployment means 17,000 troops will be on duty in the United Kingdom during the Games , compared with the 9,500 currently in Afghanistan . G4S had been expected to recruit a staff of more than 10,000 as part of a total security force of 23,700 for the Olympic and Paralympic Games . It will still provide several thousand personnel . A G4S statement Thursday said the company has about 4,000 people at work across 100 venues and has more than 9,000 others going through the required vetting , training and accreditation process . British newspaper reports Friday highlighted concerns over the training given to G4S recruits and the use of thousands of young people in security roles . G4S said the scheme to involve young people was run by LOCOG and was aimed at students . `` While they form a vital part of the security workforce , they will be performing more of a support function than the trained security personnel from G4S , or the armed forces , '' a spokesman said in a statement . Young people do a `` fantastic job '' in a similar role at the annual Wimbledon tennis championships , and there 's no reason to think they wo n't perform well at London 2012 , the spokesman said . Britain is on a heightened state of alert ahead of the Games , which open on July 27 . CNN 's Jim Boulden and Laura Smith-Spark contributed to this report .
NEW : Security firm G4S says young people employed for the Olympics will do a good job . Sebastian Coe says he is `` extraordinarily impressed with '' security contractor G4S . An extra 3,500 troops to be brought in to cover a shortfall in security staff . G4S says it has about 4,000 people at work across 100 venues ; more undergoing training .