Iran's top diplomat blamed Washington on Monday for the failure of talks after landing in Russia as part of a whirlwind diplomatic tour, with direct negotiations between the warring parties seemingly at an impasse.

Foreign Minister Abbas Araghchi made the remarks in Saint Petersburg, where he is expected to meet with Russian President Vladimir Putin, having sandwiched a trip to Oman in between visits to main mediator Pakistan over the past few days.

Islamabad played host to the first and only round of unsuccessful talks between Washington and Tehran, and Araghchi's visit had fanned hopes for fresh negotiations over the weekend, until US President Donald Trump scrapped a planned trip by his envoys Steve Witkoff and Jared Kushner.

"The US approaches caused the previous round of negotiations, despite progress, to fail to reach its goals because of the excessive demands," Araghchi said Monday.