Li-ion battery IEC 62133 compliance
Go to Farnell site, and look for Varta battery packs. Most of them have IEC 62133 as well as UN38.3 and of course RoHS.

Now the catch. You can buy IEC 62133 cells (not packs), however I assume you are gonna put it to some medical devices. That won't be accepted unless you have a battery protection board (PCM) and a thermistor integrated to the cell. 

If you do the integration on your own, you have to re-certify the cell+PCM to IEC62133. This is 4k USD at least. 

Therefore it may make sense to actually buy packs, not cells. You may prefer well known brands over some 3rd party panasonic-official-cell-integrator lab in a chinese garage.