* Prosecutors reportedly seeking seven years in prison
* Paya was winner of 2002 Sakharov Prize for human rights
* Paya family accused government of involvement in wreck
By Jeff Franks
HAVANA, Oct 4 (Reuters) - A Spanish political activist involved in a car crash that killed prominent Cuban dissident Oswaldo Paya goes on trial on Friday in a politically charged case that has strained Cuba's relations with Spain.
According to Spanish newspapers, prosecutors are seeking seven years imprisonment for Angel Carromero, the leader of the youth wing of Spain's ruling People's Party, who faces two counts of vehicular manslaughter for the July 22 accident.
Paya, 60, and dissident colleague Harold Cepero, 31, died when Carromero lost control of the small rental car he was driving and smashed into a tree near the city of Bayamo 415 miles (668 km) southeast of Havana.
They and Jens Aron Modig, a young conservative activist from Sweden, were on their way to meet supporters of Paya's Christian Liberation Movement.
Paya was awarded the European Union's Sakharov Prize for human rights in 2002 for leading the Varela Project, a campaign to reform Cuba's one-party political system.
The case touched off charges from Paya's family and other dissidents that government agents ran the car off the road, but Carromero and Modig have said no other vehicle was involved.
The Spanish government has been scrambling behind the scenes to try to get Carromero, 27, off the hook and has said little publicly about the case.
Since the conservative People's Party ousted the Socialists in an election last year, Cuba-Spanish relations have cooled and could worsen, depending on the outcome of Carromero's trial, western diplomats in Havana say.
One diplomat said Cuba is insisting that Spain publicly declare it agrees the Cuban government had no hand in the car wreck, but so far that has not happened.
Cuba has been equally tight-lipped, but staged a July 30 press conference with Modig to show that foreign involvement with Cuban opposition is not limited to its usual foil, the United States, and that dissidents get money for their activities, a charge the government uses to discredit them with the Cuban people.
Modig, who like Carromero suffered only minor injuries in the wreck, admitted giving Paya 4,000 euros ($4,900) from his Christian Democratic Party and apologized for "having come to this country to carry out illicit activities."
Shortly afterwards, he was released and sent back to Sweden, where he has kept a low profile.
The balding, lightly bearded Carromero, appearing in a video at the press conference, alluded to his biggest worry - that the case would get wrapped up in international politics.
"I ask the international community to please concentrate on getting me out of here and to not use the traffic accident that could have happened to any other person for political ends," he said.
He also downplayed his culpability in the accident, saying he "took the precaution of any other driver" by applying the brakes when he drove over a section of road that was under repair and slid out of control.
The Cuban government said he was driving too fast, did not heed warning signs about the road construction and jammed on the brakes too abruptly.
Spain is hoping Carromero avoids a fate similar to that of U.S. contractor Alan Gross, who in 2011 was sentenced to 15 years in prison for illegally setting up Internet networks in Cuba under a U.S. program promoting political change on the island.
Cuba considers the program part of longstanding U.S. efforts to topple the communist government.
Foreign diplomats in Havana generally think Carromero will not be treated so harshly, if for no other reason than Spain has a previously signed accord with Cuba that allows prisoners from their respective countries to return to their homeland to serve their sentences, if the host country concurs.
But there is also a feeling that Cuba does not want to alienate Spain - and perhaps Europe - by keeping Carromero behind bars.
"Cuba doesn't want to open another front in its ideological battles. It may not love the current Spanish government, but it doesn't hate it in the same way it does the United States, and it doesn't want to take the risk of alienating all of Europe," said a European diplomat who asked not to be named.
Elizardo Sanchez, head of the independent Cuban Commission on Human Rights, said the loss of Paya was "irreparable," but could have been worse if the dissident community was not made up of various groups.
"If the dissident movement was a monolithic movement, the loss of its leader would something devastating, terrible, but since in reality he was the leader of one group we see the other organizations working as always and the repression continues to be high," he said.