Japanese lawmakers are revisiting a plan to build a $6.7 billion natural gas pipeline from Russia ahead of a visit by President Vladimir Putin to Japan next month.

A group of about 80 lawmakers from the ruling parties will ask the government by the end of this month to carry out a feasibility study on the project, Naokazu Takemoto, the secretary-general of the group, said in an interview. The proposed pipeline linking Sakhalin island with Tokyo is estimated to be as long as 1,500 km and cost about ¥700 billion, a study by the group shows.

Prime Minister Shinzo Abe is seeking to deepen economic ties with Russia in an effort to resolve a 70-year-old row over four disputed islands off Hokkaido.