LAUSANNE, Switzerland — Negotiations over Iran’s nuclear program resumed here Wednesday but were almost immediately beset by competing claims, just hours after diplomats abandoned a March 31 deadline to reach the outline of a deal and agreed to press on. And as the latest round hit the week mark, three of the six foreign ministers involved left the talks with prospects for agreement remaining uncertain.

Iran’s deputy foreign minister, Abbas Araghchi, told reporters that if the sides make progress on the text of a joint statement, then that could be issued by the end of the day. But he suggested the statement would contain no specifics.

A senior western official quickly pushed back, saying that nothing about a statement had been decided and that Iran’s negotiating partners would not accept a document that contained no details. The official was not authorized to speak to the negotiations by name and spoke on condition of anonymity.

The German Foreign Ministry tweeted that “nothing is agreed,” although “progress is visible.”