When public buses rumble to a stop in some of Jerusalem's religious neighborhoods, women often dutifully enter by the rear door and sit in the back, leaving the front for men.

There's no law requiring the women to do so, but those who don't risk verbal taunts and intimidation.

It's a curious sight given Israel's history as an international trailblazer for women's rights.

The country produced one of the democratic world's first female heads of government with Golda Meir's election in 1969. Women lead Israel's Supreme Court and two of the nation's main political parties. Israel drafts women into military service and has some of the world's toughest laws against sexual harassment and rape.

Yet Israeli women say that recently some of their most basic rights have come under attack, including singing and dancing in public, vying for student government positions at a religious college, appearing on billboards in Jerusalem, speaking on a religious radio station and even using the sidewalk during religious celebrations.

Feminists who once thought Israel's battle for gender equality had been mostly won are warning of a new assault from Israel's fast-growing ultra-Orthodox community, which is seeking to expand religious-based segregation into the public realm.

"We are going backward and losing all our achievements," said Rachel Liel, executive director of the New Israel Fund, which advocates for civil rights and equality. "A 21st century democracy is not a place where women sit in the back of the bus."

Israel's ranking in gender equality — based upon workplace discrimination, pay differentials and other factors — compared with other countries dropped from 36th place in 2007 to 55th in 2011, according to the World Economic Forum's Global Gender Gap Index.

A study last year by the advocacy group Israel Religious Action Center, which is leading the campaign to allow women to pray as men do at the Western Wall, found that attempts to segregate men and women had expanded from private buildings and religious sites to public spaces, including a post office, pizza parlor, grocery store and fairgrounds.

"The pattern is one of creeping encroachment," said Anat Saragusti, director of Agenda, an Israeli group that works on minority-rights issues. "They try a little, see if it works, and then push the envelope a bit more every time until things reach a critical mass and are irreversible. That's when people wake up. But by that point, it's often too late."

During a religious holiday last month, male residents of Jerusalem's ultra-Orthodox Mea Shearim neighborhood banned women from using the main streets to prevent mingling of the sexes, defying a Supreme Court order allowing women on the streets. Last year, the same neighborhood constructed a separate, covered sidewalk that women were forced to use, a measure also rejected by the court as discriminatory.

The Israeli Andalusian Orchestra, based in the largely secular city of Ashdod, last month said it was dropping a female vocalist from its standard subscription schedule after conservative customers complained that it was against their religion to listen to a woman sing in public.

One way women's rights activists are pushing back is by plastering posters of themselves around Jerusalem to protest what they say is the growing trend of advertisers to self-censor female images from billboards and bus placards after many such ads were ripped down or burned.

The Israel Defense Forces, which has long been a national symbol of gender equality and opportunity for women, is facing intense criticism after scores of dancing female soldiers were shuttled away from dancing male soldiers during a public military ceremony celebrating the Sukkot holiday last month. Military officials said they are investigating the incident. A month earlier, some male cadets walked out of another official event because female soldiers were singing.

Ultra-Orthodox leaders agree that the problem is one of encroachment, but they insist that it is the secular and the liberal religious communities that are seeking to impose modern values and prevent the ultra-Orthodox, also known as haredim, from practicing a stricter form of Judaism. Those traditional values typically include restrictions on television and the Internet, modest dress codes and segregation of the sexes, which haredi leaders say is needed to protect women from sexual exploitation and men from temptation.

"Women walk down the street as though they are at the beach," said Rabbi Shmuel Pappenheim, a spokesman and leader for an umbrella group of ultra-Orthodox factions. "If in the past this was typical only of Tel Aviv, today it has reached Jerusalem as well. They encroach on our way of life, prompting our people to impose new restrictions, deepen separation and erect higher barriers to keep it away."

The conflict is gaining intensity, he said, because of the rising influence and numbers of the haredi community, once a small, scattered minority that today numbers 1 million, about 15% of the population. The ultra-Orthodox live mostly in separate cities and neighborhoods where they have been free to practice their beliefs without interference. As their political power grows, they are demanding more accommodation for their way of life, Pappenheim said.

"We used to be a small minority fighting for survival," he said. "Now we are a huge minority. As the saying goes, with food comes more appetite."

He said the segregation was not intended to discriminate or oppress women but to "protect women's honor and dignity."

Critics say the issue is not religious tolerance, but equality.

"With all due respect, women are quite capable of defending their own honor," said Hila Benyovits-Hoffman, an Israeli blogger who writes frequently about gender issues. "This insane gender separation and obsessive attention to women's bodies have nothing to do with religion. Perhaps it is sexual repression or frustration out of control."

Many activists criticize mainstream politicians for failing to speak out more aggressively against the segregation, particularly female leaders such as Kadima party Chairwoman Tzipi Livni, Labor Party head Shelly Yachimovich and Supreme Court Chief Justice Dorit Beinisch. All three declined to comment for this article.

"Israel's women politicians do not like to be associated with women's issues and do not want to be single-interest feminist activists," said Saragusti of Agenda. "But who will take care of women's issues if those who made it to the top won't?"