Half of firms in London will let their employees work from home during the Olympics or take time off to watch the Games, according to a study.

A survey of more than 250 companies in the capital by the CBI showed that most were positive about the event, believing it will boost tourism.

Almost half of those polled admitted they were still nervous about their level of preparedness for the impact of the Games.

Sara Parker, CBI London director, said: "The 2012 Games will help showcase London around the world and will be good for the economy.

"But with only a month to go, the scale of the challenge is becoming clear and some businesses are still nervous about their levels of preparedness. That's why it's crucial that all companies ensure they plan ahead, particularly for the transport and logistical challenges.

"It's encouraging that many firms are already thinking about flexible working during the Games, but with a huge influx of people expected in the capital in a matter of weeks, those who haven't prepared need to turn their attention to this as a matter of urgency."