(For a TAKE A LOOK on Honduras, click on [ID:nN28343997])

* Roadblocks by Zelaya supporters shut highways

* Pro-Zelaya protesters say will be out again on Friday

* Interim gov’t says increasing security, reimposes curfew

* Saturday talks will seek to break post-coup impasse (Adds capital’s roadblocks lifted, coffee, quotes)

By Simon Gardner and Gustavo Palencia

TEGUCIGALPA, July 16 (Reuters) - Supporters of Honduras’ ousted President Manuel Zelaya shut down commercial highways on Thursday in protests in the capital and other places, demanding his reinstatement ahead of weekend mediation talks.

The demonstrations by hundreds of Zelaya followers took place as Costa Rican President Oscar Arias prepared to host talks on Saturday with the rival sides in the political crisis triggered by the June 28 coup that toppled Zelaya.

Watched by armed soldiers and riot police, the protesters shut off the northern and southern entrances to the hill-ringed capital Tegucigalpa for several hours, backing up trucks and other vehicles for miles (kilometres) in both directions.

They later lifted the roadblocks, vowing to return in force on Friday to repeat the protests.

Police also reported protest roadblocks at Comayagua and at Copan on routes that carry exports and imports to and from neighboring El Salvador. But the interim government said commercial traffic was running over the frontiers of Honduras, an impoverished exporter of bananas, coffee and textiles.

Arias, mediating in Central America’s worst crisis since the Cold War, is due to host talks between envoys representing Zelaya and Roberto Micheletti, the interim president installed by Honduras’ Congress after the coup. After an inconclusive initial round last week, the two sides are deadlocked.

Zelaya is demanding that Micheletti comply with international calls for his immediate reinstatement.

Micheletti has said the army lawfully removed Zelaya because he violated the constitution by seeking to lift limits on presidential terms and has ruled out Zelaya’s return to office.

Arias told local radio in Costa Rica on Thursday he would try to broker a compromise, such as a national reconciliation government between the two sides or an amnesty.

MORE PROTESTS PLANNED FOR FRIDAY

The coup and impasse in Honduras is a foreign policy test for U.S. President Barack Obama, who has sought to improve ties with Latin America. Obama quickly condemned Zelaya’s ouster as illegal but faces calls from Venezuela’s leftist President Hugo Chavez, a vocal ally of Zelaya, to increase pressure on Micheletti to restore the deposed president.

To counter renewed protests by Zelaya’s backers, Micheletti’s administration stepped up security across the country and reimposed a night curfew late on Wednesday.

At the northern access route into Tegucigalpa, hundreds of protesters, many in red T-shirts and scarves and some wearing the cowboy hats common in rural Honduras, blocked the highway with rocks, shouting slogans calling for Zelaya’s return.

A similar protest shut off the southern access point.

“We want ‘Mel’ Zelaya back .... This will go on until he returns,” said food store owner Marco Martinez, 47, draped in the red and white flag of Zelaya’s Liberal Party.

Pro-Zelaya peasant leader Carlos Suazo vowed the protests planned for Friday would be bigger.

“Our actions and strategies will intensify until they (the interim government) won’t be able to resist,” he said.

With the coffee harvest largely over, producers said 2008/09 exports were not affected by unrest after the coup. But road blockades could disrupt fertilizer deliveries to farms preparing for the coming harvest in October.

Since the coup last month, supporters of Zelaya have staged almost daily protests calling for his return but have not seriously threatened the interim government.

CHAVEZ SAYS FEARS “CIVIL WAR”

Micheletti has repeated an offer to quit to promote a peaceful deal, but only if Zelaya is not returned to office.

Foreign governments worry that if Saturday’s mediation talks in Costa Rica fail, the Honduran crisis could escalate.

“I hope God doesn’t let this end up developing into a civil war, which could spill out across Central America,” said Chavez, who is well known for his incendiary rhetoric. He spoke in Bolivia at a meeting of leftist Latin American presidents.

The United States called for restraint.

“We support a peaceful negotiated resolution and urge other countries to play a positive role in achieving that and to refrain from any actions that could lead to violence,” U.S. Secretary of State Hillary Clinton said in Washington.

Venezuela’s Chavez, long a vociferous foe of the United States, repeated an allegation -- which Washington has denied -- that U.S. authorities had a hand in the coup.

“I don’t think they told Obama, but there’s an empire behind Obama. Obama is Obama, the empire is the empire,” Chavez added, using his habitual term for the United States.

Micheletti has accused Chavez of meddling in Honduras and of influencing Zelaya with his populist brand of socialism.

The Organization of American States suspended Honduras from membership on July 4.

Zelaya, who says the coup was a power grab by rich elites against him, has said Saturday’s talks are the last chance to reinstate him in 72 hours, before he pursues other strategies.

Arias said neither Zelaya nor Micheletti had confirmed they would attend Saturday’s talks.

“I’m hoping to make progress, but I’m not letting my hopes get too high,” he said. (Additional reporting by Juana Casas, Esteban Israel in Tegucigalpa, Terry Wade in La Paz; Mica Rosenberg in Mexico City; John McPhaul in San Jose; Paul Eckert in Washington; Writing by Pascal Fletcher; Editing by John O’Callaghan)