By Anthony Boadle
CARACAS (Reuters) - Venezuela's President Hugo Chavez will not attend this weekend's hemispheric summit in Colombia and will instead fly straight to Cuba to continue radiation treatment for cancer, his foreign minister said on Saturday.
The 57-year-old socialist leader said on Friday the radiation therapy was physically tiring and that his doctors were evaluating whether he should go to the "Summit of the Americas" en route to Havana for a fourth session.
"On the recommendation of his medical team, President Chavez decided not to attend this event," Venezuela's Foreign Minister Nicolas Maduro told reporters in Cartagena at the meeting of about 30 heads of state, including U.S. President Barack Obama.
"Today he leaves for Havana to continue to his treatment, which is going excellently," Maduro said.
Chavez said on Friday he planned to stay in Cuba longer than on his recent trips to complete his radiation treatment of five sessions. On Saturday, Venezuela's National Assembly legislature authorized him to leave the country for up to 90 days.
An appearance at the summit would have been a show of strength for Chavez, who has undergone three cancer operations in less than a year. Very little official information has been given about his health, including what type of cancer he has.
It would also have delighted his supporters by giving Chavez - who once at the United Nations called former U.S. President George W. Bush "the devil" - the chance to challenge Obama in front of dozens of other leaders.
Despite his cancer, Chavez is campaigning hard to win a new six-year term at an October 7 election that is shaping up to be the toughest political fight of his 13 years in power due to his ill health and a serious opposition challenge.
His opponents have criticized Chavez for seeking treatment in communist-led Cuba, his main ally, instead of Venezuela, and for keeping Venezuelans in the dark about the extent of his illness, raising suspicions that his cancer may have spread.
"To date there has been no medical report ... we do not know how serious the cancer is," opposition lawmaker Carlos Berrizbeitia said in the National Assembly.
Venezuelans do not know where Chavez had cancer or "how long the president has left to live," Berrizbeitia said.
(Additional reporting by Daniel Wallis and Deisy Buitrago; Editing by Vicki Allen)