By Max A. Cherney, Matt McKnight and Carlos Barria

SAN FRANCISCO (Reuters) -A demonstrator draped in a Free Tibet flag climbed a flagpole in front of the hotel where Chinese President Xi Jinping was due to meet with U.S. CEOs on Wednesday evening, capping a day of demonstrations against, and for, the Chinese leader.

Protesters of the Israel-Hamas war, critics of the global response to climate change and other causes all turned out for the Asia Pacific Economic Cooperation (APEC) forum in San Francisco, where global leaders and CEOs offered tempting targets.

The day began with a couple of hundred protesters obstructing San Francisco streets and entrances to the convention center area for the meetings.

But the focus of demonstrators shifted more towards anti- and pro-China during the day.

Hundreds of critics of Xi marched through downtown around noon, a major protest against the leader. They moved through the city's center, chanting "free Tibet" and "free Hong Kong."

Headed by a police escort, the peaceful group - which stretched for multiple city blocks - blocked one of the main downtown thoroughfares, as it moved in a slow circle around the convention center's perimeter.

“We can say beyond a reasonable doubt that this will be the largest anti-Xi protest during the bilateral talks hosted here in the United States in the history of Xi Jinping’s time as a dictator of China,” Pema Doma, executive director of Students for a Free Tibet, said early in the day.

Still, local television showed crowds welcoming Xi, waving huge Chinese and American flags, as well as posters of the two flags together, along a highway south of San Francisco where the presidents met. Some protesters also lined that route.

And in the evening, ahead of the meeting between Xi and U.S. CEOs, supporters and protesters initially both lined the street. That is where the flagpole climber took the message of Free Tibet up the pole.

By midevening, a couple hundred pro-China supporters dominated the block, singing and waving flags.

Demonstrators for non-Chinese causes have been active since at least Sunday, some crowds stretching for blocks. The group early on Wednesday formed a human chain that prevented some conference attendees from walking through the intersection.

"I'm actually kind of impressed by the fact that there's so few people here and they've actually kind of gummed up the works a little bit," said Gary Hughes from the advocacy group Biofuelwatch.

Protesters held signs that said "War criminals out of SF" and "From Palestine to the Philippines stop the US war machine."

Police donned protective helmets, but there were no major clashes.

San Francisco has cleaned up downtown streets for the meeting, and it had prepared for potential confrontation with demonstrators: eight-foot-high (2.4-meter-high) metal mesh barriers have been erected to keep people on sidewalks from interfering with vehicle traffic near the convention center.

The potential for disruptions around the summit site, portions of which were shut to vehicles and foot traffic, led the U.S. Department of Homeland Security to designate the meeting a national special security event, putting the U.S. Secret Service in charge of coordination of policing agencies.