The amnesty offer came amid sharp criticism from Israel and other nations over the two executions carried out Saturday.
"I urge them (collaborators) to use the 45 days and come to us alone -- the sooner the better, said Palestinian Authority Justice Minister Freih Abu Medein. "Otherwise, they would face the legal punishment."
Abu Medein said, "We will have no problem pardoning whoever comes and makes a full confession, expressing repentance, and reveals all the information he knows honestly and accurately." He set the 45-day deadline starting from January 13.
Medein said seven Palestinians, whom he described as spies, had already turned themselves in to the Palestinian Authority.
Executed by firing squads
Alam Bani Odeh, 25, and Majdi Makawi, 28, went before Saturday's firing squads after admitting they had aided Israel in a car bombing and checkpoint shooting in November. The bombing killed a Palestinian bombmaker and a leader of Palestinian leader Yasser Arafat's Fatah faction.
Hours after the executions, four other men were convicted as accomplices in an Israeli rocket attack that killed a Palestinian militia commander. The Bethlehem court condemned two men -- one only 18 years old -- to death and ordered life in prison with hard labor for the others.
"We have many cases (of collaboration), and in many of those the evidence will lead to a final conclusion," said Khaled Qidreh, Palestinian attorney general. "We are a state, and we are very concerned about security and the stability of our people."
On Sunday, an Israeli television channel showed one of the executions, carried out in a soccer field in Gaza City. The body of a bound, blindfolded collaborator twisted under a second-long fusillade from a nine-member police squad opening fire with Kalashnikov automatic rifles.
Cheers erupted from a crowd waiting outside the executions site at the sound of the barrage.
It was not clear how the footage was obtained, although the segment showed a Palestinian Authority policeman filming the execution with a video camera.
Germany, EU protest
Israeli Prime Minister Ehud Barak, in a statement, called the trials of the men "field court-martials."
"It is regrettable that the Palestinian Authority, which aspires to be a recognized entity, has recourse to show-trials, which recall dark periods of history," the Israeli leader added.
The European Union and Germany registered criticism over the executions, as did others in the international community. "The public executions open a new, bloody chapter in the Middle East conflict," said German Justice Minister Herta Daeubler-Gmelin in a Berliner Zeitung newspaper interview.
She described the executions as "a major mistake" and said she had sent a letter of protest to the Palestinian representative in Germany.
In addition, the European Union asked Palestinian leader Yasser Arafat to commute the two pending death sentences. Arafat must approve all executions.
Executions defended
In defense of the executions, Abu Medein, the Palestinian Justice Minister, said the two men deserved to die because they had a hand in Israel's killing of other Palestinians.
He said Israel has used Palestinian collaborators to track down senior members of Palestinian groups and so far managed to "assassinate" more than 18 activists in Gaza and the West Bank.
"Israel is using those collaborators as a tool in its war against us, and, therefore, we have to respond by all available means," he said.
Israel, however, has said it targets only individuals planning bombings and other attacks against Israelis.
In defense of the quick trials, Qidreh said, "We, as the Palestinian Authority, implement the law, and we gave them the opportunity to have legal representation and an open trial."
However, lawmaker Farez Kadura, head of the Palestinian Authority committee on human rights, hedged on the question of whether the trials were fair:
"In different circumstances, in the future when we have a democratic country, they will receive all their legal rights in court, which will assure them a just trial," Kadura told Israel's Channel Two television.
"But in today's situation," Kadura said, "when the Israeli government sends these people to assassinate or to kill people without a trial as has happened many times recently ... they of course can expect nothing else."
The Associated Press and Reuters contributed to this report.