A Palestine Liberation Organisation official said the government of technocrats formed last year to replace rival administrations in Gaza and the West Bank would be dissolved sometime today.
He said it would likely be replaced with a government of politicians.
Officials have said the move had been under discussion for several months because of the cabinet's inability to operate in the Hamas-dominated Gaza Strip.
But Hamas rejected any unilateral dissolution of the unity government.
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"It will be sometime today," the PLO official told AFP on condition of anonymity.
"The government will continue to function until we have a new one ... I think what's coming now is the formation of a government with politicians, not a government of technocrats."
Hamas spokesman Sami Abu Zuhri however said the Islamist movement had not been consulted and that it opposed any unilateral dissolution of the government.
"Hamas rejects any one-sided change in the government without the agreement of all parties," Zuhri told AFP.
Senior Hamas official Ziad al-Zaza, however, struck a more conciliatory note, calling on Abbas "to form a unity government with all national and Islamic factions to face Israeli occupation."
The move comes at an important time, with Hamas sources saying it is holding separate, indirect talks with Israel on ways to firm up an informal ceasefire agreement that took hold last August, ending a 50-day war in Gaza.
It was not clear whether Abbas's announcement was linked to the talks, but the PLO official said he believed that it played a role in the decision.
Another high-ranking Hamas official said he believed Abbas decided to act after receiving word of the indirect contacts.