US President Donald Trump said that he was unconcerned about reports that Iran may halt negotiations with Washington, arguing that Tehran had taken too long in the talks and insisting that preventing Iran from obtaining a nuclear weapon remained his overriding objective.

In a phone interview with CNBC's senior Washington correspondent Eamon Javers, Trump dismissed suggestions that a breakdown in negotiations would significantly alter his approach, even as oil markets reacted sharply to reports that Iran was unwilling to continue talks.