Is general supply produced by depots when they are under siege?

[Orel]

I've had quite of a number of sieges which lasted for quite a while(some for almost a year). I wonder whether this may occur due to enemy depots producing supplies during the siege which doesn't allow the enemy troops to lose strength.

[Durk]

I've had quite of a number of sieges which lasted for quite a while(some for almost a year). I wonder whether this may occur due to enemy depots producing supplies during the siege which doesn't allow the enemy troops to lose strength.

Wagons, river or sea, these allow for supply.
The way to check is to hover you mouse over the city, does it show zero or a number for supply? Depots, typically, have no impact if under siege.

[OneArmedMexican]

Once a city is under siege, neither a depot nor the city itself poduce any supplies anymore. Harbours however do as long as they aren't blocked by your ships or ice during winter.

Long sieges can happen nevertheless if a city had a huge supply pile to begin with. I sometimes am puzzled myself at how long besieged enemy stacks survive in RUS but in the end they always starve. Just be patient or amass enough troops to assault the city.