LONDON  Europeans are increasingly lashing out at the construction of mosques in their cities as terrorism fears and continued immigration feed anti-Muslim sentiment across the continent.

The latest dispute is in Switzerland, which is planning a nationwide referendum to ban minarets on mosques. This month, Italy's interior minister vowed to close a controversial mosque in Milan.

Some analysts call the mosque conflicts the manifestation of a growing fear that Muslims aren't assimilating, don't accept Western values and pose a threat to security. "It's a visible symbol of anti-Muslim feelings in Europe," says Danièle Joly, director of the Center for Research in Ethnic Relations at the University of Warwick in England. "It's part of an Islamophobia. Europeans feel threatened."

The disputes reflect unease with the estimated 18 million Muslims who constitute the continent's second-biggest religion, living amid Western Europe's predominantly Christian population of 400 million, Joly says.

Anti-Muslim sentiment

The clashes also represent a turnaround from the 1980s and '90s, when construction of large mosques was accepted and even celebrated in many cities. "I think the tide has turned," Joly says.

Indicative of the change:

• Supporters of the Swiss referendum collected enough signatures two weeks ago to call for a constitutional ban on minarets, the towers used to call worshipers to prayer. No date has been set for the vote.

• Italy's Interior Minister Roberto Maroni announced this month that he wants to close a Milan mosque because crowds attending Friday prayers spill onto the street and irritate neighbors. In April, the city of Bologna scrapped plans for a new mosque, saying Muslim leaders failed to meet certain requirements, including making public its source of funding.

• In Austria, the southern province of Carinthia passed a law in February that effectively bans the construction of mosques by requiring them to fit within the overall look and harmony of villages and towns.

• Far-right leaders from 15 European cities met in Antwerp, Belgium, in January and called for a ban on new mosques and a halt to "the Islamization" of European cities. The group said mosques act as catalysts for taking over neighborhoods and imposing Islamic ways of life on Europeans.

"We already have more than 6,000 mosques in Europe, which are not only a place to worship but also a symbol of radicalization, some financed by extreme groups in Saudi Arabia or Iran," Filip Dewinter, leader of a Flemish separatist party in Belgium, told Radio Netherlands Worldwide at the conference.

Dewinter criticized a mosque being built in Rotterdam, Netherlands: "Its minarets are six floors high. These kinds of symbols have to stop."

Although the group in Antwerp represented minority political parties from Belgium, Austria and Germany, its cause resonates elsewhere.

Construction of a mosque in Cologne, Germany, drew protests from residents last year and sparked a political debate in Berlin over concerns that it could overshadow the city's great Gothic cathedral.

In London, plans for a "mega-mosque" for 12,000 worshipers next to the site of the 2012 Olympics drew 250,000-plus opposing signatures.

Current controversies over mosques represent an anti-Muslim attitude that initially sprang up after the Sept. 11, 2001, terrorist attacks in the United States and the transit bombings in Madrid in 2004 and London in 2005, Joly says. Aggravating those views are pressures from the influx of immigrants and growing population of Muslims throughout Europe.

Other events have fueled worries that many Muslims don't accept Western values: widespread protests by Muslims after a Danish newspaper published cartoons of the prophet Mohammed in 2006, and the 2004 murder of a Dutch filmmaker, Theo van Gogh, by a Muslim extremist in retaliation for a film about abuse of Muslim women.

Restrictions could backfire

Sakib Halilovic, an imam in Zurich, says Switzerland's referendum to ban minarets "plays into the hands" of Muslim extremists by denying them a place to worship or limit what the mosque can look like.

"It will boost radical positions within the Muslim society in Switzerland," Halilovic told the Swiss Broadcasting Corp. last week.

Some moderate Muslims say those against building more mosques sometimes have legitimate concerns.

"Truthfully speaking, we don't need so many mosques," says Irfan al-Alawi, international director of the Center for Islamic Pluralism in London. "We have 1,600 mosques (in Britain) and a (Muslim) population of 1.6 million. It's become a business rather than a worship place."

Al-Alawi, who opposes the London mega-mosque, says disagreements within a mosque can cause some members to branch off and want their own new building that is unnecessary.

The mosques often don't fit in with neighborhoods or outnumber churches or other religious houses of worship, he says.