BETHLEHEM (Ma'an) -- Two vehicles belonging to Israeli company Afikim were torched Monday south of Qalqiliya, a day after the bus operator began two Palestinians-only lines in the occupied West Bank, Israeli police said.

"During the early hours of the morning two buses were torched in Kafr Qassem. Police arrived at the scene and are investigating who was behind the incident," Israeli police spokesman Mickey Rosenfeld told Ma'an.

The background of the incident is unclear and the investigation is ongoing, he added.

Drivers from the Israeli company were asked to remove all buses from the Palestinian-Israeli town following the incident, Israeli new site Ynet reported.

The arson attack comes after Israel launched two Palestinian-only bus lines in the occupied West Bank on Monday, a step an Israeli rights group described as racist.

"Creating separate bus lines for Israeli Jews and Palestinians is a revolting plan," Jessica Montell, director of the B'Tselem rights group, said on Army Radio. "This is simply racism. Such a plan cannot be justified with claims of security needs or overcrowding."

The Israeli Transport Ministry said the two new lines would "improve public transport services for Palestinian workers entering Israel" and replace pirate buses charging them "exorbitant prices".

Last November, Israeli police ordered Palestinian workers off a bus at the request of settlers.