Are you a mainland resident? If so:
1. Remuneration derived by a resident of the Mainland from an employment exercised in Hong Kong is chargeable to Salaries Tax in Hong Kong. However, the Mainland resident will be exempt from Salaries Tax if all the following three conditions are satisfied:

1(a) he is present in Hong Kong for a period or periods not exceeding in the aggregate 183 days in any 12-month period commencing or ending in the year of assessment concerned (please refer to paragraphs 15 to 18 below for details of the “Present for not exceeding 183 days” exemption condition);
(b) the remuneration is paid by, or on behalf of, an employer who is not a resident of Hong Kong; and
(c) the remuneration is not borne by a permanent establishment which the employer has in Hong Kong.
2. Where a Mainland resident renders employment services in Hong Kong but does not meet any of the conditions mentioned in paragraphs 1(a) to 1(c) above (e.g. his remuneration is paid by a Hong Kong employer), he will still be exempt under Hong Kong taxation law from Salaries Tax if his visit to Hong Kong in the year of assessment concerned does not exceed a total of 60 days.
As far as HKIRD are concerned, you are employed in Hong Kong and are therefore taxable in Hong Kong. It's up to you to claim an exemption by completing a tax return and providing documentary proof that you are eligible for the exemption.