Mike Pompeo Image Credit: AP

Singapore: US Secretary of State Mike Pompeo said Saturday he was hopeful there would be progress towards freeing an American pastor whose detention in Turkey has sparked a diplomatic crisis.

His upbeat tone came despite talks on Friday with his Turkish counterpart Mevlut Cavusoglu having failed to end the standoff surrounding Pastor Andrew Brunson, with Ankara warning that sanctions imposed by Washington would not work.

Brunson, who led a Protestant church in the Aegean city of Izmir, is at the centre of one of the most serious crises in relations between the Nato allies in years.

The pastor was moved to house arrest last week after nearly two years in jail on terror-related charges, but the change only increased tensions.

The US responded to the failure to fully free Brunson by hitting two top Turkish ministers with sanctions, prompting Ankara to threaten reciprocal measures.

At a press conference Saturday, Pompeo insisted he had a “constructive conversation” with Cavusoglu on Friday on the sidelines of a regional security meeting in Singapore.

“I made it clear that it is well past time that Pastor Brunson should be freed and be permitted to return to the United States, and the others being held by Turkey also similarly must be freed as well,” he said.

“I’m very hopeful that we will make progress on that in the days and weeks ahead,” he added.

However Cavusoglu struck a less positive tone after his meeting with Pompeo, also calling the talks constructive but warning that threats and sanctions would not work.

Apart from Brunson, two Turkish employees of US consulates in Turkey are also currently in jail on terror charges and another is under house arrest, while several Americans have been caught up in the crackdown that followed a failed 2016 coup.

The standoff appears to be one of the most serious fallouts between the two Nato allies in modern history, along with the rows over the 1974 Turkish invasion of Cyprus and the 2003 US-led invasion of Iraq.

Pompeo insisted Saturday Washington would continue to work with Ankara despite the row. Turkey “is a Nato partner with whom the United States has every intention of continuing to work cooperatively”, he said.