Is it permissible to prevent beggars from asking for money in mosques, and is it permissible to give to them?

There is no harm in collecting donations in mosques, and there is no argument for those who forbid it. However, solicitors are prevented if they step over people's necks or walk between rows, causing disturbance to worshippers. They are also prevented during the Friday sermon due to the obligation of listening attentively, and because their soliciting distracts people from listening to the sermon.