Israeli police clashed with Palestinian youths after entering the al-Aqsa mosque complex in East Jerusalem.
Police say they entered the site “to prevent riots”. They were reported to have used tear gas and stun grenades, and were attacked with rocks and fireworks.
Similar clashes took place at the end of July.
Al-Aqsa is one of Islam’s holiest sites and is in the Temple Mount/Haram al-Sharif site also revered by Jews.
The holy compound is a source of religious and political tension between Israel and the Palestinians. It is a frequent flashpoint for violence.
The clashes come hours before the start of the Jewish New Year, Rosh Hashanah.
Police were quoted in the Israeli media as saying the Palestinian youths who had barricaded themselves into the mosque were planning disruption to prevent Jews visiting the site.
Security forces launched a surprise raid at around 06:45 (03:45 GMT) in the hope of opening the site as planned, Haaretz newspaper reports.
The police said in a statement that masked youths within the mosque “threw stones and fireworks” and that pipe bombs had been found.
They denied reports from some witnesses that they had entered the mosque itself, saying that they had locked the doors to keep the youths inside.
An Israeli police spokesman said there had been no injuries, but according to some Palestinian witnesses several people were wounded.
There were reports of further clashes outside the compound, in Jerusalem’s Old City, and Israeli police are now said to be patrolling its narrow alleyways.
One Palestinian woman, Khadijeh Khweis, told the AFP news agency that they had been prevented from entering al-Aqsa mosque.
“They were chasing us with (stun) grenades and it’s been like that since the morning,” she said.
“We could only pray in front of the doors (leading to the complex).”
Palestinian President Mahmoud Abbas condemned what he called an “attack by the occupier’s military and police against the al-Aqsa mosque and the aggression against the faithful who were there”.
Public Security Minister Gilad Erdan said the site was now open to Jews wanting to visit for Rosh Hashanah, which begins at sunset on Sunday and continues until Tuesday evening.
And he warned that he was reconsidering what he called “the customary arrangements” of the site, saying it was “unthinkable” that Palestinians could make the area “their stronghold”.
Tensions have been running high in the city since Israel Defence Minister Moshe Yaalon last week banned two Muslim groups which confront Jewish visitors to the compound.
Mr Yaalon said the groups were the main sources of tension and violence at the site and said banning them was necessary to public order. – BBC News