Dennis Rodman, the flamboyant former basketball player who has managed to engage with North Korea’s leader — something United States officials have been unable to do — said he planned to return to the North to try to gain the release of an imprisoned American citizen, according to a video posted Friday on the celebrity news Web site TMZ.

Mr. Rodman, who went to Pyongyang in February along with three Harlem Globetrotters and a documentary film crew, told the interviewer that he planned to return to the North on Aug. 1. He did not elaborate on how he was gaining entry.

The man he hopes to free, Kenneth Bae, is a Korean-American who was recently sentenced to 15 years of hard labor on charges of committing “hostile acts” against North Korea. Mr. Bae ran tours into the North, according to South Korean human rights activists, but on Friday, North Korea accused him of being a Christian missionary plotting to build a proselytizing base within the isolated country with an aim of toppling the government.

The activists have described him as a devout Christian. North Korea, a Communist country, has traditionally considered Christian missionaries among its worst enemies.