Action Images via Reuters / Tony O'Brien Livepic
Andy Murray in action during his match against Spain's David Ferrer at the Barclays ATP World Tour Finals.
The venue has sent out an email to ticket holders telling them to allow extra time for security checks and not to bring any bag bigger than a handbag or laptop bag.
Here's the text of the email:
Following the events from Friday evening, we have reviewed security operations in place around this year's Barclays ATP World Tour Finals.
The O2 already has enhanced security in place, and the tournament continuing as normal. Venue security is monitored at all times to ensure the safety of all our visitors.
No food or drink will be allowed into the arena itself and all bags will be searched.
No bags larger than a small laptop bag or handbag will be permitted in The O2 during the tournament and visitors are urged to travel light, as there is no storage on site.
Please allow extra time for security checks.
129 people died across 6 separate terrorist attacks in Paris on Friday. ISIS has since claimed responsibility for the attacks and CIA director John Brennan has warned the terrorist organisation is likely planning more attacks.
Prime Minister David Cameron said on Monday that British intelligence agencies have foiled 7 terrorist plots in the last 6 months alone.