Palestinian negotiator Saeb Erekat has accused al-Jazeera TV of putting his life in danger by leaking secret papers on the peace talks with Israel.
The documents suggest the Palestinians were ready to make big concessions, despite public claims to the contrary.
But in an interview with the BBC, Mr Erekat admitted that some of the material was true. He had initially dismissed it as a "pack of lies".
He has vowed to take responsibility if the leaks came from his office.
The Palestinian Authority (PA) has been rocked by the revelations which show that in private meetings with Israeli negotiators, Palestinian negotiators appeared to offer compromises on issues including the status of Jerusalem, Jewish settlements, and the right of return for Palestinian refugees.
Mr Erekat has featured prominently in al-Jazeera's coverage of what it says are 1,600 documents related to the Middle East peace process. The Qatar-based channel started publishing the documents this week, along with the UK's Guardian newspaper.
"Today what is being practised against us [by the al-Jazeera coverage] is that we are guilty, we should be executed, and then after our execution, we should be given an unfair trial," he told the BBC on Wednesday, following his return to Ramallah from meetings in Cairo.
The latest cache of papers revealed on Tuesday suggested that the PA co-operated with Israeli security officials to kill its own people.
The documents cited what they said was a 2005 conversation between Palestinian Interior Minister Nasr Yousef and Israeli Defence Minister Shaul Mofaz in which they talked about assassinating a prominent militant, Hassan al-Madhoun.
Mr Madhoun, of the Al-Aqsa Martyrs' Brigades - a militant group linked to the Fatah faction of Palestinian leader Mahmoud Abbas - was later killed in an Israeli missile strike in Gaza.
After the release of the papers, the Aqsa Brigades said they held Israel responsible for the the attack, not the PA. But in the Gaza Strip, run by Fatah's rival movement Hamas, hundreds of people rallied against the PA.
Hamas official Sami Abu Zuhri told Reuters news agency that the documents "represent clear evidence of the involvement of this [PA negotiating] team in the killing of Palestinian resistance fighters".
The documents also suggest that Britain's intelligence service, MI6, was intricately involved in attempts to weaken the militant group Hamas, before it took control of Gaza four years ago. The British plan is said to recommend the detention without trial of middle-ranking Hamas officials.
Despite the revelations, Mr Erekat was carried aloft amid throngs of supporters when he returned to the West Bank from Cairo on Tuesday.
A defiant Mr Erekat challenged al-Jazeera to publish the official Palestinian papers on Jerusalem, borders, settlements, refugees and other core issues.
But he admitted that at least some of the information in the leaked confidential documents was true. The rest, however, were "half-truths" and "total fantasies" that had been taken out of context.
He said that there was now an investigation into where the leaks came from.
"If these documents were leaked from this office, I, and I alone, will hold the responsibility," he told the BBC.
But the overall impression is of a disconnect between the Palestinian leadership and the people, because the former has been prepared to say things privately that it wouldn't say in public, our West Bank correspondent Jon Donnison reports.
Al-Jazeera is gradually publishing 1,600 confidential documents from more than 10 years of secret US-brokered Middle East peace talks.
They outline major concessions Palestinians offered during talks, which were rejected by Israel. They include:
- a formal offer to allow Israel to annex all but one of the Jewish settlements built in occupied East Jerusalem
- an international committee to take over Jerusalem's Temple Mount, which houses the Dome of the Rock and Al-Aqsa Mosque - Islam's third holiest site
- limiting the number of Palestinian refugees returning to 100,000 over 10 years
The channel will reveal the fourth and final set of documents on Wednesday evening.