Lebanon has accused the United Nations refugee agency of intimidating refugees to prevent their return to Syria and on Friday blocked residency applications for the agency's staff.
"Minister of Foreign Affairs and Expatriates Gebran Bassil issued instructions... to stop the requests for residency presented to the ministry and (those already submitted) for the UNHCR in Lebanon until further notice," a statement said.
"Bassil asked for the study of other progressive measures... in the case that the UNHCR is determined to pursue the same policy," it said.
The small Mediterranean country hosts an estimated 1.5 million people displaced by the war in neighbouring Syria -- more than a quarter of its population before the conflict.
Bassil late Thursday warned his country would start taking measures against the office of the UN High Commissioner for Refugees over allegations the agency was preventing Syrian refugees from returning home.
"We sent a mission that verified that the UNHCR is intimidating the displaced who wish to return voluntarily," he tweeted.
A UNHCR spokesman responded by denying that the agency's staff were discouraging refugees from considering a return.
"We do not discourage or oppose returns taking place based on an individual decision," William Spindler told reporters.
"But in our view, conditions in Syria are not yet conducive for an assisted return, although the situation is changing and we are following closely," he said.
UNHCR spokeswoman Lisa Abou Khaled said the agency had not received any official notification of a suspension of residency permits for its foreign staff.
She declined to comment on how such a step might affect the work of UNHCR in Lebanon, but said most of the UN agency's staff were Lebanese.
"There are about 600 staff working at UNHCR here in Lebanon and the vast majority of them are Lebanese," she said, without giving a specific a number of international staff.
Lebanon has seen its water, electricity and waste removal infrastructure strained by the influx of Syrian refugees.
But international non-governmental organisations also say their presence has helped stimulate the economy.
In April, the UNHCR suggested that the government-organised return of 500 refugees was premature, explaining that it was not involved due to the prevailing humanitarian and security situation in Syria.
The world body's position infuriated Bassil, who warned Lebanon could "re-evaluate" the UN agency's work.
Lebanon is expected to soon have a new government after last month's parliamentary elections.
Syrian refugees are a recurring topic in Lebanon's political debate, but Bassil has taken a hard line and is the only leading politician directly attacking the UN.
More than 350,000 people have been killed in the Syrian war millions have been displaced since it started in 2011 with the brutal repression of anti-government protests.
But Syria's regime has retaken more than half of the country since Russia intervened in 2015 on its behalf.