European powers and Iran made little progress on Monday toward reaching an agreement to end the standoff over Tehran’s nuclear program as an end-of-March deadline closes in, The Associated Press (AP) reported.

“We’re still making progress but there is a long way to go if we’re going to get there,” British Foreign Secretary Philip Hammond said after talks in Brussels with his French, German and Iranian counterparts plus European Union foreign policy chief Federica Mogherini.

The talks are geared towards turning an interim 2013 deal into a permanent agreement.

Under the interim deal, Iran committed to limit its uranium enrichment to five percent and is gradually winning access to $4.2 billion of its oil revenues frozen abroad and some other sanctions relief.

Talks to reach a permanent deal have continuously stalled and two deadlines for a final deal have been missed.

“It’s always useful to talk but we, the French, want a solid deal,” French Foreign Minister Laurent Fabius said after Monday’s talks, according to AP.

“Certain points are yet to be resolved, we hope we will be able to resolve them but as long as it’s not done, it’s not done,” he added.

Mogherini, who is negotiating with Iran on behalf of the world’s five nuclear powers and Germany, said that all sides were aware how important it is to seal a good deal and that it was not clear whether “a technical solution” to fill the remaining gaps can be found.

“I see the elements for a deal to be reached but I still see the gaps that need to be filled,” she was quoted as having said.

Ahead of the meeting, German Foreign Minister Frank-Walter Steinmeier urged his international partners and Iran to “seize this opportunity” of talks in Brussels and in Switzerland this week to finally clinch an elusive deal.

Senior officials from the world powers will continue negotiations with Iran in Lausanne, Switzerland on Wednesday.

U.S. Secretary of State John Kerry said on Saturday he hoped it would be possible to reach an interim deal with Iran “in the next days” if Tehran can show that its nuclear power program is for peaceful purposes only.

On Friday, however, a senior European diplomat said that while nuclear talks between Western powers and Iran have made progress, some very difficult issues remain.