Iranian President Hassan Rouhani, already under pressure from conservatives for his tentative opening to the West, was criticized Tuesday for what his opponents called a "lavish ball" thrown by the first lady.

Held in a palace of the deposed Shah Mohammad Reza, in wealthy northern Tehran, the all-female dinner was held to mark Women's Day on Saturday, which coincides with the birthday of the Prophet Muhammad's daughter Fatima, a paragon of Muslim virtue.

But hard-liners in parliament said the event showed Rouhani was indulging in luxury while normal Iranians suffer economic hardship, caused in part by Western economic sanctions.

"It is most shocking and regrettable that even a pure innocent gathering cannot escape an orchestrated chorus of gossip, slander and politically motivated lies filling the air," his office said in a statement.

"All Islamic proscriptions were observed in this event . . . women turned out in traditional folk dress . . . only a few little girls capered and rejoiced," the statement added, to deflect impressions of a Western-style party, attended also by foreign guests and families of diplomats. Rouhani's wife, Sahebeh Arabi, has been slightly more visible than other first ladies in Iran and on some occasions had been photographed attending an educational or charity event, always clad in a long black chador.