The U.N.'s chief relief official for Palestinians is urging Jordan to stop discriminating against Palestinian refugees fleeing the Syrian war and open its borders to them.

The commissioner general of the U.N. Relief and Works Agency for Palestinian Refugees says "all refugees should be treated equally."

Filippo Grandi told reporters Monday that Jordan has been burdened by some 2 million Palestinian refugees over decades. But he disagreed with Jordan's decision to close the border last year to Palestinian refugees and called on Amman "to exercise maximum humanitarian efforts."

Last year, the New York-based group Human Rights Watch praised Jordan's admission of some 140,000 Syrian refugees but said officials have arbitrarily detained Palestinians in a holding center without any options except to return to Syria.