Kolkata (PTI): The West Bengal government is making "changes" in the security detail for External Affairs Minister Pranab Mukherjee following instructions from the Centre which recently reviewed it following intelligence inputs that militant groups were planning an attempt on his life.

"Instructions have been received from the Centre three days ago. His security is not being merely stepped up, but there will be some changes to make the arrangements more appropriate," secretariat sources said.

The state's role in the security for VVIPs under 'Z-Plus' category was limited to following the instructions of the Director Security, they said.

Stating there were variations in the security drills for 'Z-Plus' VVIPs, they said, "for example, additional arrangements are made when they are in vulnerable areas."

Mukherjee's security was recently reviewed following intelligence inputs that militant groups had carried out a reconnaissance to plan a suicide attack on him.

In reply to a question, the sources said the Centre had not given any instruction to the state government on the security of Chief Minister Buddhadeb Bhattacharjee who is also covered under 'Z-Plus' security.