South Korea is on alert for many types of potential disruptions when it hosts global leaders next week for a key economic summit. South Korea's president thinks a potential attack on land or sea by rival North Korea is unlikely.

South Korean President Lee Myung-bak on Wednesday was asked by reporters how worried he is about North Korea disrupting the Group of 20 leaders' summit in Seoul.

The president says he does not believe Pyonygang would do something. He adds, the South Korean government is looking at various possible moves North Korea and terrorist groups might make and is carrying out thorough security preparations.

North Korea's official ruling party newspaper denies Pyongyang intends to disrupt the meeting. It terms Seoul's heightened security something of an "extremely provocative and foul nature" intended to create a "brutally confrontational climate" that will heighten tensions on the Korean peninsula.

The North and South briefly exchanged artillery fire last Friday across the border.

South Korea's navy Wednesday morning fired warning shots in the Yellow Sea at what it said was a North Korean fishing vessel, which sailed south of the Northern Limit Line, the de facto maritime border.

During next week's G20 meeting, police say the most likely disruptions will come from anti-globalization demonstrators.

A massive protest at the last summit in Toronto turned violent as banks and other business were vandalized and police cars set on fire.

Security officials here say they intend to keep demonstrators cordoned in an official protest zone far from the summit site.

Twenty-thousand riot police will be backed by other officers and security personnel in and around a triple-tiered two-kilometer security ring.

The G20 summit will be held in the South Korean capital next Thursday and Friday. It will bring an unprecedented number of global leaders to Seoul, including the presidents of the United States, China, France, Russia and Brazil and the prime ministers of Britain, Canada, India, Italy and Japan.