Cologne cathedral
Security in the heart of the city will be high especially around landmarks such as the cathedralGetty

A four-day no-fly zone is just one of the precautions being set up as part of tight security arrangements ahead of the far-right AfD's party conference in Cologne this weekend.

Commencing from today (20 April) the restriction on air traffic will take hold, running until after the conference for the Alternative for Germany party this weekend.

More than 4,000 police officers will be patrolling the centre of the city as the party conference takes place ahead of September's general election.

Part of the security concern is that officials expect some 50,000 protesters – including left-wing extremists – to descend upon the city to counter the AfD, with organisers calling for participants to "block" the party conference at a central hotel as a form of "civil disobedience".

The no-fly zone will apply to almost all flights, including model airplanes and unmanned aviation devices.

The only exceptions made will be for German military and police aircraft, as well as for any rescue or emergency aircraft.

The ban also excludes flights following aviation regulations that are going exclusively to and from Cologne-Bonn airport, or to and from Nörvenich, where there is an air base.

The far-right party's conference will also be a test of the AfD's strength as it has struggled with a bitter power struggle which threatens to scupper its bid to win its first seats in the Bundestag.

At the height of the migrant influx, the party polled at around 15% but have since struggled to get above single figures with bitter infighting amongst the senior members.

The AfD has lost momentum as the number of new refugee arrivals to Germany has dwindled over the last several months.

The Social Democrats (SPD), junior partners in Angela Merkel's governing coalition, have also managed to claw back some support since appointing a new Merkel challenger, former European Parliament president Martin Schulz.

The no-fly zone according to Cologne police