Iranian officials closed ranks on Sunday to criticise the US for backing a series of pro-democracy demonstrations after thousands staged a fifth night of protests in Tehran.

There were reports of smaller demonstrations in at least two other cities, a sign that the momentum of the protests, which Washington have hailed as a cry for freedom, may be gathering pace.

Iran’s Foreign Ministry accused the US of ‘‘flagrant interference in Iran’s internal affairs’’ and said the significance of the protests was being deliberately overstated by US officials.

‘‘The Americans ignore the presence of millions of people to welcome the supreme leader and President, but they call the protests of a few individuals the voice of the people,’’ Foreign Ministry spokesman Hamid Reza Asefi said in a statement.

Iran’s clerical establishment is unnerved by mounting US pressure since the end of the war in Iraq.

While venting most of their anger at unelected clerics who wield ultimate power in Iran, protesters have also lambasted moderate President Mohammad Khatami. They accuse him of failing to deliver promised improvements in democracy, justice and social freedoms after six years in power.

The US had earlier expressed ‘‘alarm’’ over Iranian government’s ‘‘violent’’ handling of ongoing students-led protests and expressed support for Iranians who aspire for democracy, freedom and the rule of law.

‘‘We are alarmed at reports of arrests and provocative actions taken against students by regime forces, and call upon the regime to protect the human rights of the students and to release those who have been arrested,’’ said a White House statement released yesterday.

By using the word ‘‘regime’’ for the Iranian government, the US was indirectly questioning its legitimacy, analysts noted.