A global backlash against U.S. President Donald Trump's immigration curbs gathered pace on Sunday as several countries including long-standing American allies criticised the measures as discriminatory and divisive.

Governments from London and Berlin to Jakarta and Tehran spoke out against Trump's order to put a four-month hold on allowing refugees into the United States and temporarily ban travellers from Syria and six other Muslim-majority countries, which he said would help protect Americans from terrorism.

In Germany - which has taken in large numbers of people fleeing the Syrian civil war - Chancellor Angela Merkel said the global fight against terrorism was no excuse for the measures and "does not justify putting people of a specific background or faith under general suspicion", her spokesman said.

She expressed her concerns to Trump during a phone call and reminded him that the Geneva Conventions require the international community to take in war refugees on humanitarian grounds, the spokesman added.

Merkel's sentiments were echoed in Paris and London; "Terrorism knows no nationality. Discrimination is no response," said French Foreign minister Jean-Marc Ayrault, while his British counterpart Boris Johnson tweeted: "Divisive and wrong to stigmatise because of nationality."

Along with Syria, the U.S. ban affects travellers with passports from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen.

Trump said his order, which indefinitely bans refugees from Syria, was "not a Muslim ban", though he added he would seek to prioritise Christian refugees fleeing the war-torn country.

Washington's Arab allies, including the Gulf states and Egypt, were mostly silent.

The government in Iraq, which is allied with Washington in the battle against ultra-hardline Islamist group Islamic State and hosts over 5,000 U.S. troops, also did not comment on the executive order.

But some members of the parliament said Iraq should retaliate with similar measures against the United States.

In Baghdad, influential Shi'ite cleric Moqtada al-Sadr said American nationals should leave Iraq, in retaliation for the travel curbs.

"It would be arrogance for you to enter freely Iraq and other countries while barring to them the entrance to your country ... and therefore you should get your nationals out," he said on his website.

There was no immediate reaction to the curbs from Islamic State, although in the past it has used U.S. monitoring of Muslim foreigners to stoke Muslim anger against Washington.

(Source: Reuters)