The UN refugee agency said Monday it was "alarmed" by the consequences of US President Donald Trump's order barring refugee arrivals, describing those targeted as "anxious, confused and heartbroken."
"This week alone, over 800 refugees were set to make America their new home," the Geneva-based UNHCR said in a statement.
The order signed by Trump on Friday suspends arrivals by refugees in general for 120 days and Syrian refugees indefinitely.
"UNHCR estimates that 20,000 refugees in precarious circumstances might have been resettled to the United States during the 120 days covered by the suspension," the statement added, basing that figure on averages over the last 15 years.
"Refugees are anxious, confused and heartbroken at this suspension," it further said, describing UNHCR chief Filippo Grandi as "deeply worried" by the impact of Trump's move.
Refugees who qualify for resettlement to the US or other developed countries have typically endured extreme hardships and have no prospect of safely returning to their home countries.
The US president's widely-condemned executive order also bars entry for travellers from seven mainly Muslim countries -- Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen -- for 90 days.