The ministry responsible for immigration and security said no dangerous individuals were among those who had bypassed the border checks. However, there is no way to confirm this information.
The numbers of people getting into the country without getting checked on the British border were released under a Freedom of Information request to Press Association. According to the data, the UK Border Force recorded 2,394, 2,665 and 2,278 misdirected passengers in 2013, 2014 and 2015 respectively — adding up to over 11,000 people.
The Home Office have reportedly branded the revealed figures as unacceptable.
When a passenger gets beyond border controls without getting clearance from immigration officers, a so-called "misdirection" is logged, with an average of sex people per day "misdirected" by airport staff. Misdirection can happen when wrong doors open at the arrival gate or passengers are shown the wrong way by airport workers.
"We are determined to eradicate these errors and believe a civil penalty is a vital tool in ensuring this happens," the Home Office spokesperson said.
Secure borders are of paramount importance for British authorities, with "taking back control" over immigration into Britain serving as main arguments of staunch Brexit supporters in the country.
British lawmakers consider setting fines for airports and airlines up to $66,000 for misdirecting passengers.
A spokesman for the AOA said the proportion of misdirected passengers as a percentage of total travellers has fallen since 2013.
He said this demonstrated that operators' efforts to tackle the problem are having an effect.
"We are committed to working with airlines, ground handlers and Border Force to continue to improve on our track record. We do not believe that the proposed civil penalty should be part of that ongoing work as it is disproportionate in light of the numbers of passengers involved," an Airport Operators Association spokesman said.