Abbas said that he received information about the alleged plot a month ago.
"The information was confirmed by our security. But what the security was trying to verify was the exact time and date. But I went to Gaza anyway," Abbas said.
Jamal Nazzah, a Fatah spokesman, told Al Jazeera: "This is not the first time Hamas has tried to kill Abbas. In our view this was part of a plan to make a coup against the Palestinian Authority."
But Atef Adwan, a Hamas MP, said: "If Hamas had wanted to kill president Abbas, then we would have done this years ago."
"We don't want to do this as president Abbas represents the legality of the Palestinian system."
The video footage appears to show Hamas fighters preparing explosives in a tunnel under the main north-south road that runs through the middle of the Gaza Strip, a road Abbas uses to get to his compound when in Gaza.
The images appear to show Hamas fighters laughing as one seems to say: "This is for Abu Mazen and the next one is for the Preventative Security."
Abu Mazen is a name by which Abbas is also known.
Red Sea summit
The tape was released on the same day that Abbas agreed to meet Ehud Olmert, the Israeli prime minister, for the first time since Hamas took control of Gaza.
Abbas and Olmert will meet at the Egyptian Red Sea resort of Sharm el-Sheikh on Monday, officials said.
Hosni Mubarak, the Egyptian president, and Jordan's King Abdullah will meet Abbas there on Sunday before the four-way summit, demonstrating support by neighbouring Arab states for Abbas.
Before the meeting, Israel's cabinet is expected to agree on Sunday to release hundreds of millions of dollars of Palestinian tax revenues collected by Israel.
They have been withheld for the past 15 months since the Hamas movement formed a Palestinian government after winning a parliamentary election.
An official in Olmert's office told reporters that the summit would demonstrate Israeli and Arab support for Abbas. Israel would agree to strengthen relations with Abbas and could lift some restrictions in the West Bank if Abbas pledges to confront armed groups there.
In Ramallah on Thursday, the central council of the Palestine Liberation Organisation (PLO) affirmed Abbas's most recent steps against Hamas – throwing it out of the government, outlawing its armed groups and forming an emergency cabinet of moderates.
|Abbas said he went to Gaza despite |
knowing of the plot against him [AFP]
Although largely inactive in recent years, the PLO considers itself the sole representative of the Palestinian people.
The PLO body also asked Abbas to prepare for new presidential and legislative elections, and to change the electoral system.
But Hamas spokesman Sami Abu Zuhri dismissed the PLO's decisions as "illegal and illegitimate".
Hamas has said it considers new voting as theft of its 2006 election victory and would not permit it in Gaza.
Abu Zuhri hinted that fighters would also disrupt balloting in the West Bank.
"I think they [Abbas and his advisers] must learn from the Gaza lesson," he said. "They didn't catch [in time] what happened in Gaza, and they must be awake before paying a high price elsewhere due to their policies," he said.
In a poll published on Thursday by the independent Palestinian Centre for Policy and Survey Research, three-quarters of Palestinians said they favour early elections.
The poll among 1,270 Palestinians also indicated that Abbas only had a narrow lead over Ismail Haniya, the deposed prime minister from Hamas, at 49 per cent to 42 per cent.
The PLO Central Council also called for dissolving all militias, presumably including the Al-Aqsa Martyrs' Brigades, which is linked to Fatah.
But this appeared to be largely lip service to blunt criticism that Abbas outlawed the Hamas forces but did not move against his own.
Al-Aqsa fighters have cracked down on Hamas in the West Bank in the past few days and it is unlikely Fatah would rein them in at a time of confrontation.