Thousands of Palestinians flocked Monday at the Al-Aqsa Mosque in Israel-occupied East Jerusalem for nighttime Tarawih prayer on the first day of Ramadan.

Tarawih is a voluntary prayer performed during the fasting month after the last evening prayer or Isha.

According to a statement by the Islamic Endowments Department in Jerusalem cited by the official Palestinian news agency WAFA, nearly 35,000 Palestinians performed the prayer at Al-Aqsa Mosque.

The agency, however, quoted eyewitnesses as saying that Israeli forces prevented many young men from entering the mosque and beat at least one Palestinian near Bab al-Zahra, one of the gates leading to Al-Aqsa Mosque, before detaining him.

Asked about Israeli forces blocking hundreds of Palestinians wanting to perform the first Tarawih prayer from entering Al-Aqsa Mosque on Sunday, U.N. spokesperson Stephane Dujarric said: "We're always very concerned about any provocation in the holy sites in Jerusalem."

Al-Aqsa Mosque is the world's third-holiest site for Muslims. Jews call the area the Temple Mount, claiming it was the site of two Jewish temples in ancient times.

Israel occupied East Jerusalem, where Al-Aqsa is located, during the 1967 Arab-Israeli War. It annexed the entire city in 1980 in a move never recognized by the international community.

Tensions have been running high across the occupied West Bank since Israel launched a deadly military offensive against the Gaza Strip after a cross-border incursion by the Palestinian resistance group Hamas last October.

At least 420 Palestinians have since been killed and more than 4,600 others injured by Israeli weapons fire, according to the local Health Ministry.

Israel stands accused of genocide at the International Court of Justice (ICJ), which in an interim ruling in January ordered Tel Aviv to stop genocidal acts and take measures to guarantee that humanitarian assistance is provided to civilians in Gaza, where more than 31,000 people have been killed.