THE AFL will increase security presence at ANZ Stadium and the MCG for this weekend's preliminary finals after authorities raised the terror alert level.The League was briefed by Victorian chief police commissioner Ken Lay and his team during the week about what the new alert level means for sporting events.AFL CEO Gillon McLachlan and MCC chief executive Stephen Gough both attended the meeting, while the League has had discussions with ANZ Stadium management about Friday night's Sydney Swans-North Melbourne game.Measures will include more security staff and a greater diligence when checking the bags of those entering stadiums.McLachlan stressed to football fans the measures were precautionary, but warned they may experience a slight delay when lining up to enter the ground."I think you'll see a more visible (security) presence," McLachlan said on 3AW on Friday morning."What everyone should be comfortable with is that we're being precautionary."McLachlan said the security checks were a necessary part of putting on a major event."Hopefully they'll (fans) be understanding and they'll get there a little bit earlier just in case," McLachlan said."It shouldn't be too bad but it may have a little impact."However, McLachlan said he was not concerned about attending the Hawthorn-Port Adelaide clash at the MCG on Saturday, and hoped fans would feel the same."People understand where it's at at the moment and we're just being prudent in stepping things up a bit," McLachlan said."I certainly feel very comfortable going along there tomorrow (Saturday) night."