The total number of roadblocks in the Palestinian territory rose from 566 on September 4 to 607 by April 29, the UN Office for Coordination of Humanitarian Affairs (OCHA) said.
A total of 144 new closures were erected while 103 were removed, an OCHA report said.
The closures severely restrict the mobility of people and goods within the West Bank, and also affect access of UN staff crossing from the West Bank to Jerusalem, the agency added.
The international community has urged Israel to ease restrictions on movement in the West Bank as part of peace efforts with the Palestinians.
During a visit by US Secretary of State Condoleezza Rice in March, Israel pledged to remove 50 West Bank roadblocks.
Israeli authorities later claimed they did away with 61 roadblocks, but OCHA said only 44 had actually been removed and that most of those were of little or no significance.
Israel started installing the roadblocks, some staffed by soldiers and others unmanned, during the first Palestinian uprising in the late 1980s in order to curb militant attacks on targets in Israel.
The number of barriers increased during the second uprising which began in 2000.
'Israel doing its utmost'
The report came out shortly after visiting French Foreign Minister Bernard Kouchner criticized Israel's network of roadblocks and checkpoints, which are seen as a key impediment to the recovery of the Palestinian economy.
"The restrictions on access and mobility are still significant," Kouchner said at a Palestinian investment conference in Bethlehem. "They have not yet been alleviated as they should have. Israel should and Israel can exert more efforts in this regard without endangering its security."
Israel says it cannot move faster in easing restrictions because Palestinian militants still pose a threat.
Israeli government spokesman Mark Regev, speaking before the OCHA report was published, said Israel is doing its utmost to improve freedom of movement in the West Bank.
"That's our challenge to take down roadblocks, to try to create greater movement and access for Palestinians while maintaining security. That's what we're trying to do," He said.
AFP and The Associated Press contributed to this report