Russia's gas export monopoly Gazprom is in talks with Nigeria to spend up to $2.5 billion on developing its vast natural gas reserves, a senior Nigerian gas official said on Saturday.

The Russian company is on a global hunt for new reserves and has emerged as one of the leading suitors to Africa's top energy producer as it reforms its gas sector.

"Gazprom has come twice to visit the federal government. They want to invest in Nigeria in gas exploitation, gathering and processing," a senior Nigerian government official working on gas policy told Reuters.

Gazprom has offered to invest between $1 billion and $2.5 billion to begin with, he added. A Gazprom spokesman was not immediately available to comment.

Nigeria is the world's eighth-biggest exporter of crude oil but even though it has the seventh-largest proven gas reserves in the world it has not developed its gas industry to anywhere near full potential.