* Around 30 sites proposed as barracks in the north
* Signatories say funding may be a problem - document
* Talks punctured by occasional tensions
By Emma Farge
BAMAKO, Feb 18 (Reuters) - Malian rebels agreed on Tuesday to confine members of their armed groups to barracks in U.N.-led preliminary talks in the capital, according to sources who attended and a copy of the agreement seen by ...