'Rajoub's men', youths in jeans, swinging rifles, loiter outside the door. Despite the 40C heat, there is a chill in Mr Rajoub's dingy Jericho headquarters. This figure, in his colonel's fatigues, bald, with a thin moustache, who spent 17 years in Israeli jails (he threw a grenade at a lorry carrying Israeli troops) was once a national hero. Now his men are feared by many Palestinians.
'Why are your own people afraid of you?' Mr Rajoub stiffens and the finger stabs out again. 'Why you ask such questions? What is it you want?' Then, curling his lip, he said: 'If my own people fear me it is because they know they have done something wrong. They have done something dark in their past. My role is only to protect the people. To ensure human rights and freedom of speech.'
For all the colonel's bravado, all is not well in the Palestinian security forces. There are signs of disarray in the agencies set up by Yasser Arafat, chairman of the Palestine Liberation Organisation. A member of Mr Arafat's presidential guard was shot dead by Mr Rajoub's forces in the West Bank town of Tulkarm on Saturday.
The incident was seen as the opening shot in a struggle for power between Mr Rajoub's and Mr Arafat's supporters. 'What incident in Tulkarm? Nothing happened in Tulkarm,' Mr Rajoub says. 'There are many people causing trouble, pretending to be security when they are not. I have the power to control such people. I have the manpower.'
Mr Arafat is accused by some Palestinians of using Mr Rajoub, and his Gaza counterpart, Mohamed Dahlan, to quash dissent. It was 'Rajoub's men' who threatened the pro-Jordanian newspaper, al-Nahar, leading to its closure last month. The paper reopened this week, taking a more pro-PLO stance.
More serious than internal squabbles is Israeli pressure on the Palestinian security forces to act against their own militants. Hamas, the Islamic Resistance Movement, and Islamic Jihad, continue to attack Israeli targets. At the week-end an Israeli soldier was shot dead in Gaza by Islamic Jihad gunmen.
Yitzhak Rabin wants Mr Arafat to round up Palestinian militants. Otherwise, says Mr Rabin, there will be no extension of autonomy. This week Mr Arafat's officers in Gaza rounded up 36 members of Islamic Jihad. Mr Arafat now faces pressure to act against Hamas. There are demands for the PLO to extradite suspects to Israel.
The Israeli pressure presents Mr Arafat with a dilemma. If anti-Israeli attacks continue, Mr Rabin will refuse the PLO more concessions. But to act as Israel's policeman may ignite a serious conflict between the PLO and the Palestinian opposition, who say their military actions are in revenge for Israeli actions.
Many Palestinian families support both camps. Mr Rajoub's brother, Youssef Rajoub, was arrested recently by Israel for membership of Hamas. As Israeli pressure mounts, Mr Arafat may have to unleash Jibril Rajoub to do Mr Rabin's bidding. When Palestinian police arrested 20 Hamas activists in mid-August, Hamas threatened a 'military jihad in Gaza'. Most suspects were released quickly. Mr Rajoub says a confrontation with the opposition is unlikely. He says he has a 'good relationship with Hamas'. He says he is 'trying to convince the people to respect the agreement and to tell the opposition not to violate the agreement . . . not because we like the Israelis or we want to make Rabin glad, but because we think it is good for our people.'
Asked if would hand over Palestinian militants to the Israelis, Mr Rajoub shrugs. 'You have another question?' Outside, the large black steel gate closes as more of 'Rajoub's men' drive by.