Israel said Jamil Jadallah was planning a major attack
He was speaking ahead of an expected meeting between the Israeli foreign minister and Palestinian leader Yasser Arafat, and just before a visit to the region by British Prime Minister Tony Blair.
"Myself, I am going to lead all the negotiations, I really believe in that," Mr Sharon told leaders of the World Jewish Congress in Jerusalem on Wednesday.
His comments came as at least one Palestinian was killed by Israeli helicopter gunships that fired missiles at a car containing three people in the West Bank city of Tulkarm.
Israeli radio reported that a second passenger might also have died and that the Israeli military had captured the third man, who was badly injured.
The radio said another Palestinian, an official from the Palestinian militant group Hamas, was abducted by commandos from the village of Beit Iba, west of Nablus in the northern West Bank.
Palestinian scorn
Mr Sharon's offer of talks has been met with scorn by Palestinian officials.
Israeli security forces killed six Palestinians on Wednesday, including a senior member of Hamas, Jamil Jadallah, who was accused by Israel of organising a suicide bombing at a Tel Aviv disco on 1 June in which 20 teenagers died .
Mr Arafat condemned his killing as an "assassination".
A senior Palestinian official, Nabil Shaath, said Mr Sharon had "not shown any signal aiming to achieve peace" and his aim was "killing, destruction and aggression".
Repeated escapes
Israeli sources said Jadallah, who was killed in Hebron by a helicopter rocket, had been planning new attacks inside Israel.
Mr Sharon's office said Jadallah had escaped Palestinian custody four times and the Palestinian Authority had "provided him protection and allowed him to continue his activities in Hamas' military wing".
According to Palestinian sources, Israeli troops also killed another member of Hamas, Abdullah Jaroushi, in Tulkarm.
In other incidents in the West Bank, Israeli troops killed two members of Mr Arafat's Fatah faction and two Palestinian policemen.
They also arrested Mujahed Abu Jalboush, a member of the militant Islamic Jihad group, during a raid on the Palestinian-controlled village of Arrabe, near Jenin.
Islamic Jihad was allegedly behind an attack on Sunday in the northern Israeli town of Hadera, in which four Israeli women were killed.
No pull-out
Israel has so far dismissed international calls to pull its troops out of four West Bank towns, saying the army will withdraw from its positions only when the Palestinians guarantee security.
Mr Sharon has said this includes the arrest and handover of those behind the assassination of cabinet minister Rehavam Zeevi.
Israel moved forces into and around Palestinian-run towns in the West Bank on 17 October in response to the assassination of Zeevi.