Liquid tight conduit into a distribution panel

[Noway2]

This morning during a project meeting where we were discussing making some wiring modifications to our building, the question was raised as to whether or not it was permissible to run liquid tight (flexible) conduit into a distribution panel or if we would need to use rigid (we avoid EMT) and then put an LB on it to convert. Our electric shop / code guru did not know the answer to this one. I was wondering if anyone knows whether or not this is permitted and perhaps the relevant code section?

 

[Noway2]

Followup: I may have posted this to the wrong forum. I thought it said NEC, not IEC issues. Sorry...