JERUSALEM (Reuters) - Five protesters scaled a landmark Jerusalem bridge on Thursday and hoisted a banner urging visiting U.S. President Barack Obama to halt Arctic oil exploration.

The protest by environmental group Greenpeace was staged a short distance from a conference hall where Obama was later due to deliver a keynote speech to Israeli students.

Defying tight security, the environmentalists used climbing gear to clamber up the cables of the 118 meter-high (390 feet) suspension bridge and unfurled a yellow banner that read: "Obama: Stop Arctic Drilling".

A Greenpeace Israel official said the five climbers, two Israelis and three foreigners, scaled the bridge as part of the group's world-wide campaign to ensure the Arctic remains a nature reserve.

The United Nations' Environment Programme said in February that the Arctic needs to be better protected from a rush for natural resources as melting ice makes mineral and energy exploration easier.

Police spokesman Micky Rosenfeld said eight other activists who had earlier tried to climb the bridge were arrested before they could make their way up the cables.

(Writing by Ori Lewis; Editing by Erica Billingham)