Yes- within 12 months from the date of first filing of the priority application.

For national phase of PCT application-within 30 months from the earliest priority date. 

Worldwide- 

required 

1. A Power of Attorney, simply signed. 
2. One copy of the English specification and claims.
3. One set of the drawings relating to the invention, if any.
4. An abstract of the invention 
5. A deed of assignment signed by the inventor, if the applicant is not the inventor.
6. A certified copy of the application giving the filing date, number and country if the application is to be filed with a priority claim.

Note Please note that the priority document has to be submitted within 3 months from the earliest priority date

For PCT applications entering the national phase in the Sri Lanka, a copy of the PCT international publication search and examination reports must be submitted with the application.

Twenty (20) years starting from the Sri Lanka filing date, (in case of PCT, starting from the PCT filing date). The term of protection is non-extendable

If the patent is not exploited within 5 years from the date of grant, it will be subject to compulsory licensing.

Annuity is payable from the 2nd year up to the end of the 20th year.