Is it safe to put expanding foam around boiler flue

[beema]

I recently notice during the cold spell that there was a draft coming from my wall mounted boiler. On closer inspection I discovered that there was a 3 "gap above my boiler right through the wall above it. I could see daylight!
I mentioned it to a plumber who was fitting my new bathroom. He sealed the gap with a flame-proof foam filler. It looks a bit like polystyrene.
However, i did not see the packaging of the product he used. I am a bit worried as I did not know that there was such a thing as expanding flameproof foam filler. The space it fills gets very hot and in in colder weather It will be very hot for long periods of time. I am concerned that it may just bee flame retardent not proof. In our local DIY shop all the fillers are contracindated at over 25 degrees. Can anyone let me know if there is such a flameproof product?

[beema]

Thanks for your Link- i feel happier now !