CAIRO • The United States and other Western governments must accept the new reality that Islamists have emerged to fill the power vacuum in the Arab world after a wave of popular uprisings, Human Rights Watch said in its annual report Sunday.

The New York-based group also urged Islamist parties, which have emerged as the biggest winners in recent elections in Tunisia and Egypt and are expected to fare well in Libya, to respect the rights of women and religious minorities, saying they cannot "pick and choose" when it comes to human rights.

Islamist parties are "genuinely popular" in the Arab world, said HRW's executive director, Kenneth Roth, warning that "ignoring that popularity would violate democratic principles."

"Being a political Islamic government should not be a reason to turn a government into a pariah," Roth told reporters in Cairo, where the group released its annual report.

The Arab Spring revolts began in Tunisia in late 2010 and quickly spread to Egypt, Libya, Yemen, Syria and Bahrain, deposing or challenging authoritarian rulers as citizens who long seemed incapable or unwilling to rise against decades of repression took to the streets in a stunning awakening.

Since the collapse of the regimes in Egypt and Tunisia a year ago, Islamist groups once largely confined to the political sidelines, such as the Muslim Brotherhood, have formed parties and contested parliamentary polls, winning the greatest share of seats.

In some ways, the unexpected Arab uprisings have amounted to a slap to the United States and other Western governments, which had supported autocratic regimes that served as bulwarks against Islamists hostile to the West and appeared to offer stability in a volatile region.

"The West backed an array of autocrats as long as they, in turn, supported Western interests," Roth said. "The West is still adjusting to this historic transformation."