Below are the only regulations I have been able to find where it states that you have to report reaching a level.
French NAT-region AIC:
http://www.sia.aviation-civile.gouv....2007_13_EN.pdf
1. report leaving a flight level as soon as you begin your climb or descent ;
2. similarly, report reaching a flight level as soon as you are level ;
3. in RVSM airspace, provide the reports even if ATC has not specifically requested them.
Canadian AIP:
RAC - 8.0 INSTRUMENT FLIGHT RULES (IFR) ? EN ROUTE PROCEDURES
Although the CARs do not specifically direct pilots to report altitude information to ATC, pilots, if not operating in radar airspace (i.e. radar-identified by ATC), should report reaching the altitude to which the flight has been initially cleared. When climbing or descending en route, pilots should report when leaving a previously-assigned altitude and when reaching the assigned altitude.
Hong Kong AIP:
http://www.hkatc.gov.hk/HK_AIP/AIP/ENR/HK_ENR1.8.pdf
Except in a radar environment, pilots shall report reaching any level assigned within RVSM airspace