Class II

Yes, an EU manufacturer producing class IIa medical devices must have ISO 13485 implemented.

In MDR, there is a requirement that the manufacturer must have implemented a quality management system. Also, there is a requirement that the manufacturer must follow harmonized standards published by the EU Commission. On that list of harmonized standards, ISO 13485:2016 is the only standard that is a management standard. 

Here is the link to harmonized standards: https://ec.europa.eu/growth/single-market/european-standards/harmonised-standards/medical-devices_en

Perhaps the following information can be useful:

Six key benefits of ISO 13485 implementation - https://advisera.com/13485academy/knowledgebase/six-key-benefits-of-iso-13485-implementation/

If you need to speed up ISO 13485 implementation, perhaps this could help - Free webinar on demand – How to use a Documentation Toolkit for the implementation of ISO 13485 - https://advisera.com/13485academy/webinar/how-to-use-a-documentation-toolkit-for-the-implementation-of-iso-13485-free-webinar-on-demand/

Excuse me to write back on this point. But am i correct in saying that if the manufacturer does not have ISO13485, then it's the responsability of the Notified Body to audit the said manufacturer and see that he is producing according to MDR requirements. In which case the Notified Body will be mentioned on the DOC issued. Isn't this also enough for MDR requirements? thank you.

According to the MDR, the manufacturer must have implemented a quality management system. It does not need to be certified (there is no such requirement), but documentation and processes need to be implemented. Notified Body will during MDR audit also audit the quality management system. 

The Notified Body must be mentioned on the Declaration of Conformity for all classes besides class I – only for medical devices that are issued on the market as self-declaration.

These articles can provide you further information: 

EU MDR – Easy-to-understand basics https://advisera.com/13485academy/what-is-eu-mdr/

First-, Second- & Third-Party Audits for medical device manufacturers & suppliers https://advisera.com/13485academy/knowledgebase/first-second-third-party-audits-for-medical-device-manufacturers-suppliers/