Move follows a Turkish court's decision to keep US pastor Andrew Brunson in jail during his trial on terrorism and spying charge
Six US senators have introduced bipartisan legislation to restrict loans from international financial institutions to Turkey "until the Turkish government ends the unjust detention of US citizens," a Senate committee statement said.
The move on Thursday followed a Turkish court's decision the day before to keep US pastor Andrew Brunson in jail during his trial on terrorism and spying charges, a case that has deepened a rift with NATO ally Washington.
The bill, dubbed the Turkey International Financial Institutions Act, directs the US executive of the World Bank and European Bank for Reconstruction and Development to oppose future loans, except for humanitarian purposes, to Turkey, the Senate Committee on Foreign Relations statement said.
'There is no concrete evidence against me. The disciples of Jesus suffered in his name, now it is my turn'
- Andrew Brunson, detained pastor
Brunson is among around a dozen US citizens who have been jailed and face long prison sentences for allegedly playing a part in a failed 2016 coup against Turkey President Recep Tayyip Erdogan.
The committee said the opposition should continue until Turkey is "no longer arbitrarily detaining or denying freedom of movement to United States citizens (including dual citizens) or locally employed staff members of the United States mission to Turkey".
Brunson, a Christian pastor from North Carolina who has lived in Turkey for more than two decades, was indicted on charges of helping the group that Ankara blames for the failed coup, as well as supporting the outlawed PKK group.
Brunson, who denies the charges, was pastor at the Izmir Resurrection Church, where he served a small Protestant congregation in Turkey's third-largest city. He faces up to 35 years in jail if found guilty.
"It is really hard to stay in jail and be separated from my wife and children," Brunson told the court in Turkish at the hearing on Wednesday in the town of Aliaga, north of Izmir.
'A total disgrace that Turkey will not release a respected US Pastor, Andrew Brunson, from prison. He has been held hostage far too long'
- US President Donald Trump
"There is no concrete evidence against me. The disciples of Jesus suffered in his name, now it is my turn. I am an innocent man on all these charges. I reject them. I know why I am here. I am here to suffer in Jesus's name."
On Wednesday, US President Donald Trump tweeted: "A total disgrace that Turkey will not release a respected US Pastor, Andrew Brunson, from prison. He has been held hostage far too long.
"@RT_Erdogan should do something to free this wonderful Christian husband and father. He has done nothing wrong, and his family needs him!"
US rejects linking of Gulen case
The US and Turkey have been formal military allies since Turkey joined the NATO in 1952, but relations have been fraught in recent years on issues ranging from Turkey's involvement in Syria's civil war to Washington's refusal to extradite Fethullah Gulen, a US-based cleric Ankara says was behind the failed coup.
Turkey is continuing to press for the extradition of Gulen, who denies the charges and lives in a secluded compound in the state of Pennsylvania.
On Friday, a senior US official rejected any linking of the case of Brunson with Gulen.
"One of the aspects of the tension in the relationship has been when people, including people in the [Turkish] government, have drawn very direct linkages (between Gulen and Brunson)," said the official, speaking to the AFP news agency and asking not to be named.
"Very senior people have suggested that," he added. "We do not think it is appropriate to link these cases, partly because the legal systems are very different in the two countries, and the cases are very different."
In September last year, Erdogan suggested that Turkey could free Brunson if Washington handed over Gulen in a swap deal.
"Give him (Gulen) to us, and we will try (Brunson) and give him back," Erdogan said then.
Turkey has expressed exasperation at the failure of the US to hand over Gulen to face trial, although the official said there was now an increase in communication between Ankara and US legal authorities.
The official said Turkey had presented a "large quantity" of information about Gulen but said "the issue is 'is there sufficiently clear evidence of Fethullah Gulen's personal involvement in the coup?'" to allow extradition.
The official said that the US has long kept an eye on Gulen, who has lived in self-exile in the country since 1999.
"We have been investigating the Gulen movement for longer than the Turkish government has," said the official, in an apparent dig at past cooperation between Erdogan's ruling party and the Gulen movement.