Hydrographers from India and Pakistan on Monday formally began a 20-day joint survey of Sir Creek, a 65 mile-long marshy strip off the Gujarat coast, to finalise maps which would help the two countries demarcate the disputed maritime boundary of the area.

The hydrographers met onboard an Indian ship at Sir Creek and held discussions, officials in Islamabad said.

Officials from both sides finalised the modalities of the survey during their meeting in Islamabad on December 23 and the process was going on as per schedule.

The survey would be conducted on land as well as off the coast to verify the outermost points of the coastline in the disputed area based on the principle of equidistance.

This is the second survey being conducted in Sir Creek in as many years. The first survey, conducted last year, covered the horizontal section of the creek.

External Affairs Minister Pranab Mukherjee, after talks with his Pakistani counterpart Khurshid M Kasuri, told reporters on Sunday that the officials would be directed to expedite their work on Sir Creek.

Last month's talks between hydrographers centered around modalities to coordinate the joint survey of Sir Creek and the adjoining areas without prejudice to the positions of the two countries.

The two sides simultaneously held discussions to finalise the maritime boundary whose determination was delayed due to the dispute over marshy strip.