(Adds diplomats about behind doors talks)
TEGUCIGALPA, Nov 28 (Reuters) - The result of Honduras' presidential election was in limbo on Tuesday, with diplomatic sources saying closed-door negotiations were holding up the announcement of a winner despite clear signs that a gregarious TV host was on course for a surprise victory.
Among the poorest nations in the Americas, Honduras has been blighted by years of gang violence, giving it one of the world's highest murder rates.
Incumbent Juan Orlando Hernandez, who won praise in the U.S. government for helping tackle the flow of migrants and deporting more drug cartel leaders, had been expected to win before the vote.
But a delayed, partial count on Monday morning pointed toward a victory for TV entertainer Salvador Nasralla, 64. Inexplicably, election authorities have not given any more results since.
Official results may not come until Friday or Saturday, one diplomat said, a lag that risks stoking tension in a violent country that suffered a coup in 2009.
Nasralla, a self-described centrist, headed a left-right coalition called the Opposition Alliance Against the Dictatorship, and claimed victory on Monday - as did Hernandez.
Election official Marcos Ramiro Lobo told Reuters on Monday afternoon that Nasralla was leading by a margin of five points, with about 70 percent of ballots counted.
The only results officially released so far came out early on Monday morning and showed a similar lead for Nasralla with 57 percent of ballots counted.
Lobo said Nasralla appeared certain to win, signaling that experts at the electoral body regarded his lead as irreversible.
Even so, Honduran officials still seemed far from declaring an official winner. On Tuesday, Hernandez reiterated that he had won, and refused to concede, telling supporters they should wait for final results.
"Nobody can call it an irreversible trend," he said, "Not even 60 percent of the ballots are counted."
The election tribunal's delay in publishing results was due to difficult negotiations between Hernandez's National Party, which had assumed it would win, and Nasralla's outsider alliance, according to two European diplomats who spoke on condition of anonymity.
Behind closed doors, the parties are discussing immunity from prosecution for current officials and how to carve up positions in government, the diplomats said.
Hernandez's National Party appears set to retain control of Congress in the election, giving it the second-most important perch in the country.
The European Union's chief observer for the election, Marisa Matias, urged officials to maintain an open channel of communication as they finalized the results.
"After two days without announcing new results, the Supreme Electoral Tribunal must establish a more fluid communication, making public balances of partial results," she said.
The electoral body was so certain that Hernandez would win that it showed unprecedented transparency during the contest, one of the diplomats said. That left the body with little room to maneuver when Nasralla came from nowhere to take a strong lead.
Nasralla's lead appears too large for Hernandez to overcome, Lobo told Reuters on Monday. He did not say what percentage of the vote Nasralla secured. The initial tally encompassing more than half of ballots early on Monday gave Nasralla 45 percent and Hernandez 40 percent.
With a booming voice and finely coiffed hair, Nasralla is one of the country's best known faces as the host of game shows that feature scantily-clad women by his side.
He is backed by former President Manuel Zelaya, who was ousted in a 2009 coup after he proposed a referendum on his re-election. The possible return to a position of influence for one-time leftist Zelaya risks fuelling concern in Washington.
The United States has longstanding military ties to Honduras and few ideological allies among the current crop of Central American presidents. In Mexico, leftist Andres Manuel Lopez Obrador leads opinion polls for next year's presidential election.
Hernandez, 49, was credited with lowering the murder rate and boosting the economy, but he was also hurt by accusations of ties to illicit, drug-related financing that he denies.
His bid for a second term, which was made possible by a 2015 Supreme Court decision on term limits, divided opinion in the coffee-exporting nation of 9 million people. (Editing by Julia Love and Alistair Bell)