* "'71" deals with Northern Ireland "troubles"
* Keitel, Whitaker feud in "Two Men in Town"
* Germany's "Jack" shows boys living rough in Berlin (Adds screening for Northern Ireland movie "'71")
By Michael Roddy and Gareth Jones
BERLIN, Feb 7 (Reuters) - Two powerful films, one looking at the plight of boys abandoned in Berlin, the other about an ex-convict haunted by his violent past, kicked off the competition for best picture at the 64th Berlin International Film Festival on Friday.
A third competition film, the Northern Ireland-conflict themed "'71" capped the day with a harrowing look at a British soldier's plight when he is left behind in a rebellious Catholic nationalist neighbourhood after his patrol gets ambushed in a riot in Belfast.
French-born British director Yann Demange said the title of "'71" came from the time in the Northern Ireland "troubles" when the lines between Protestants and Catholics were not yet set in stone. The soldier separated from his patrol, and new to Belfast, has no idea where he is and becomes a pawn in the increasingly murderous game between the two sides.
"Belfast was a kind of a forerunner for the kinds of insurgencies most Western European or most Western armies now find themselves involved in," screenwriter Gregory Burke told a post-screening news conference.
Demange told Reuters that his film could not have been made had it not been for Paul Greengrass's "Bloody Sunday" and Steve McQueen's "Hunger", both dealing with "troubles" themes.
"Those two films meant that this film could exist because those films had to happen first and of course they're amazing movies," he said.
German director Edward Berger's "Jack", starring the immensely persuasive first-time child actor Ivo Pietzcker in the title role, is the story of the 11-year-old and his blonde-haired younger brother Manuel finding their way through a labyrinth of Berlin's streets and its drugged-out nightlife.
It is one of four German films vying for the festival's top prize, to be awarded next week.
Berger's film shows the older of the boys rising to the challenge of survival after his unmarried mother puts him in a children's home because she cannot cope with the two at home.
Jack is bullied there and almost drowned by his main tormenter. He then runs away and embarks on an odyssey with his brother Manuel around Berlin to find his mother.
"This is not always reality but it can happen," Berger told a news conference.
Berger said he had deliberately tried not to make the film "Berlin-specific" in order to portray the universal problem of young people growing up in broken families.
"Right from the start we decided not to show the cliches," screenwriter Nele Mueller-Stoefen said. "We showed her (the mother) in a caring way, but we show Jack taking responsibility, which is something that happens often in a family."
"It was a great fun because when we did a shoot I didn't have to go to school," said the young actor Pietzcker.
By contrast, "Two Men in Town" unfolds far from the city, in the desert border country of New Mexico.
Directed by French-Algerian Rachid Bouchareb, it stars Forest Whitaker as an ex-convict whose murder of a deputy is not going to be forgotten by Harvey Keitel's sheriff.
Whitaker's character tries to build a new life after 18 years in jail, with the help of his new faith in Islam and a girlfriend played by Mexican actress Dolores Heredia.
He is also supported by his feisty parole officer, played by Britain's Brenda Blethyn, who tries to shield him from the sheriff's vindictive desire to put him back in jail.
Whitaker gives an intense portrayal of a man - calm and courteous much of the time but hungry for love - struggling to repress the raw anger that once turned him into a killer.
The film, inspired by a 1973 French film of the same name with Alain Delon, explores the interplay of humanity and rules, immigration - the long wall marking the border with Mexico is a brooding presence - and the search for personal redemption.
"I wanted to readapt completely to the Mexican border ... I met several sheriffs who ... were very sensitive to the drama of immigration, when it goes badly," director Bouchareb said.
"At the same time, there is a rigidity in the application of the laws, in the construction of the wall, there is a violence in all this," he told a news conference.
Bouchareb said he and his team spoke with political activists, police officers, prisoners, Muslim clerics and Afro-American Muslims while researching the film.
"Forest (Whitaker) gives us the American vision because we are not American," he added.
Blethyn, who played the title role in the TV detective drama "Vera", described having to work on her American accent for the film.
"One of the obstacles for me was that she (the parole officer) was from Illinois and I had all these more southern accents around me so it was hard for me to hold on to that Illinois accent. But I am told I managed it," she said. (Editing by Robin Pomeroy)