your post is purely temporary and co-terminus with the duration of the project

2) it is for ICAR to take a call on your promotion

3) The Indian Council of Agricultural Research (ICAR) is an autonomous body responsible for co-ordinating agricultural education and research in India. It reports to the Department of Agricultural Research and Education, Ministry of Agriculture.The Union Minister of Agriculture serves as its president

4) make representation to the ministry of agriculture for framing of guidelines for promotion of project staff

This appears to be a contractual employment.

What was the conditions that have been stated in the employment offer letter?

Actually may fall under the IMD and not under ICAR for the purposes of promotion benefits and other emoluments.

The host institute's guidelines need not be applicable to your funding agency especially if the host institute do not have such facilities to accommodate you in the higher grade. The host institute can reject our candidature too if there is no post available with them to the promoted cadre.

You may refer to the promotion and other service conditions or policies by which your employment is governed as per the employment offer letter to find if there is any clause biding on the host institute to oblige this.