Israel launched two Palestinians-only bus lines in the occupied West Bank on Monday, a step an Israeli rights group described as racist and which the Transport Ministry called an improvement in service.

The left-wing Haaretz daily reported the ministry opened the lines, to be used by Palestinian labourers travelling between the West Bank and Israel, after Jewish settlers complained that Palestinians on mixed buses were a security risk.

"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 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".

"The Ministry of Transport has not issued any instruction or prohibition that prevents Palestinian workers from travelling on public transport in Israel nor in Judea and Samaria," it said, referring to the West Bank.

"Furthermore, the Ministry of Transport is not authorised to prevent any passenger from using public transport services."

Rights groups, however, voiced concern that Israeli police at checkpoints in the West Bank would remove Palestinian passengers from regular bus lines and order them to use the new ones.

Police spokesman Micky Rosenfeld said all Palestinians returning to the West Bank would be searched for stolen property, describing this as a routine Israeli precaution.

He said he did not know whether and how this might affect Palestinian travel on regular buses.

Herzl Ben-Zvi, mayor of the Karnei Shomron settlement, said the new lines "answer the needs of all passengers - Palestinians and settlers" because they would relieve overcrowding on buses in the area.

Israel captured the West Bank in the 1967 Middle East war and maintains a network of roadblocks in the territory. Palestinians seek the West Bank, along with the Gaza Strip and East Jerusalem, for a future state - a claim supported by most world powers, which view the settlements as illegal.