JERUSALEM, Aug. 2 (Xinhua) -- Thousands marched in Jerusalem's annual Gay Pride parade under heavy police security in the conservative city on Thursday.

At least 10,000 people attended the parade, but local media widely assessed the number of participants at 22,000, making the event the largest pride parade in Jerusalem's history, said police spokesman Micky Rosenfeld.

Dozens of activists with the ultra-nationalist organization of Lehava rallied near the parade, holding anti-gay posters and shouting homophobic slogans. "Four suspects were arrested for causing public disturbances in the area during the parade," Rosenfeld said.

Some 2,500 security personnel took part in securing the event, remembering 2015 fatal knife attack in which a man killed a 16-year-old girl and injured five others.

"Police security measures were implemented in the center of Jerusalem to prevent any incidents at the parade," Rosenfeld said.

Television broadcasts showed thousands of people holding rainbow gay flags and marching from the starting point at the Liberty Bell Park to the Independence Park in central Jerusalem. They held signs with slogans such as "There's love in me, and it will win," "Love your neighbor as yourself," and "Pride and equal."

Some marchers held posters condemning the government as "homophobic," referring to a recent law that denies surrogacy from gay couples and single men.

"This parade is the ultimate answer to the rampant incitement against the gay community and clearly proves that there are many in the Israeli public who refuse to accept it," Tamar Zandberg, leader of the left-wing party of Meretz, told the Hebrew-language Ha'aretz newspaper.

Jerusalem's annual parade is modest in comparison to Tel Aviv's festive parades with hundreds of thousands of participants.