(Adds comments from experts)
By Alex Dobuzinskis
Feb 5 (Reuters) - The last surviving members of the U.S. Congress to have served in the Korean War have sent a letter to North Korean leader Kim Jong-un asking him to release imprisoned American missionary Kenneth Bae.
North Korea in December released 85-year-old Korean War veteran Merrill E. Newman, a former U.S. special forces soldier who had been held since October after visiting the country as a tourist, and the members of Congress applauded that in the letter seeking Bae's freedom.
"You have done the right thing by releasing a fellow Korean War veteran, Merrill E. Newman, to return home, you would be making further progress on the humanitarian front by freeing Kenneth Bae to reunite with his family," stated a copy of the letter obtained by Reuters on Wednesday.
The letter, signed by Democrat Charles Rangel from New York, Democrat John Conyers Jr. from Michigan, Republican Sam Johnson from Texas and Republican Howard Coble from North Carolina, is not seen as having nearly as much influence on the North Korean leaders as a possible visit from a U.S. envoy.
Bae, 45, has been held for more than a year by North Korea, which convicted him of trying to overthrow the state and sentenced him to 15 years of hard labor. Rangel and a congressman from Washington state, where Bae lived, invited his family to attend President Barack Obama's state of the union speech last month.
Bae's sister, Terri Chung, said in an interview she was grateful to the four congressmen for calling attention to her brother's situation. "When there's more awareness of Kenneth's plight, I think that's always a good thing," she said.
Chung said Bae's Seattle-area family has not spoken to him since a Dec. 29 phone call, one of three that North Korea has allowed Bae to have with his family since his detention in November 2012. Bae's mother was permitted to visit him in Pyongyang in October.
Academic experts on North Korea said the letter was not likely to sway authorities there to free Bae.
"I don't think they really care what four members of Congress think ... whether they're Korean War veterans or not," said Daniel Sneider, associate director for research at the Asia-Pacific Research Center at Stanford University.
"They want someone coming to pay homage to them, and maybe they have something they want to communicate and they want to communicate it at that level," Sneider said.
A U.S. official, speaking on condition of anonymity, said last month that an offer had been made to send U.S. North Korean rights envoy Robert King to Pyongyang to secure Bae's release. King has not been sent to North Korea on that mission, and how North Korea responded to the offer is not clear.
Rangel, who was wounded in the Korean War and was awarded the Purple Heart and Bronze Star for his service, had mentioned Bae's case in a letter last year to North Korea that pleaded for the release of Newman, who was still detained at the time.
The letter from the four congressmen was dated Tuesday and came as North and South Korea agreed to allow some families separated by the 1950-53 Korean War to hold brief reunions.
The meetings between families from the two countries are planned for Feb. 20 to Feb. 25 in Mount Kumgang, just north of the border, South Korea's Unification Ministry said.
In their letter, the congressmen urged Kim Jong-un to extend the reunion effort to the roughly 100,000 Korean-Americans with family in North Korea. (Additional reporting by Lesley Wroughton in Washington)