The US has signalled that it will not be drawn into the role of a mediator between India and Pakistan, saying both countries should work together to resolve their differences.

Asked during the daily briefing on Tuesday if Secretary of State John Kerry had offered to mediate between the two neighbours on the Indus Waters Treaty dispute, State Department Spokesperson John Kirby replied bluntly: "As I said, we encourage India and Pakistan to work together bilaterally to resolve their differences."

Kirby confirmed that Kerry spoke with Pakistan Finance Minister Mohammed Ishaq Dar last Thursday but would not give details of their conversation.

A Pakistan Finance Ministry statement on Friday gave Islamabad' version of their talk.

Asked if Kerry had discussed the Indus dispute with Indian officials and at what level, Kirby said: "We're in regular communication with the Indian and Pakistani governments on a wide range of issues. I just don't have any more details for you."

"The Indus Waters Treaty has served, I think as you know, as a model for peaceful cooperation between India and Pakistan for now 50 years," he said.

"We encourage, as we have in the past, India and Pakistan to work together to resolve any differences."

According to Pakistan Finance Ministry, Kerry made the call to Dar.

Seeming to invite that Kerry had asked for Washington's intervention, according to the ministry, "Dar indicated that US support on the principles and legal position of Pakistan will be greatly appreciated".

According to the ministry statement, Dar also told Kerry that the "Indus Waters Treaty is an international commitment and it is the responsibility of the World Bank to make sure that India honours this."

The statement said Kerry told Dar "that the President World Bank (Jim Yong Kim) had recently informed him about Pakistan's complaint against India on the subject of the treaty".