NEW : However , it ca n't guarantee natural gas transit to Europe . Fight to continue over debts owed to Russia by Ukraine . The process will be ` ` gradual '' Gazprom operates the world 's largest natural gas distribution network .
NEW : Belarus says it ca n't guarantee natural gas transit to Europe . Talks to continue over debts owed to Russia by Belarus . Gas cuts will be `` gradual '' Gazprom operates the world 's largest natural gas distribution network .