GAZA, Sept 2 (Nidal al-Mughrabi/Reuters) - Hamas said on Thursday its militants would keep on attacking Israelis and denounced peace talks between Israel and the West Bank-based Palestinian government due to start in Washington later in the day.

Israeli forces have boosted security measures and Palestinian police have rounded up more than 500 Hamas suspects in the West Bank since a gunman for the Islamist group killed four Jewish settlers there on Tuesday.

Hamas controls the Palestinian Gaza Strip, while Palestinian President Mahmoud Abbas's Fatah party governs the West Bank.

Operations of resistance will continue and the measures by the occupation and Fatah will not block them, said Hamas spokesman Sami Abu Zuhri.

Abbas is to meet Israeli Prime Minister Benjamin Netanyahu at the State Department later on Thursday for the first direct peace talks for 20 months, but Hamas remains opposed to negotiations with Israel.

Mahmoud Abbas does not have the right to speak for the Palestinians, nor to represent them and therefore, any results will not be binding on the Palestinian people, Zuhri said.

Hamas has also claimed responsibility for a second attack this week in the West Bank, a shooting on Wednesday that wounded two Israelis near another Jewish settlement in the territory that Palestinians seek for a future state.

As well as rounding up Hamas suspects, West Bank authorities have vowed additional measures to prevent further violence.

The West Bank government, Zuhri said, was nothing but a tool to protect the security of the occupation and settlers. (Writing by Allyn Fisher-Ilan; Editing by Jon Hemming)