PARIS, Oct 6 (Reuters) - France plans to strip five dual nationals of French citizenship for their part in a 2003 bombing in Casablanca that killed at least 45 people, the interior minister said on Tuesday, stepping up plans to combat terrorism.

While Britain last year unveiled powers to strip suspected Islamist militants of their passports temporarily, France has so far used the judgment sparingly even though hundreds of jihadists from France have joined Islamist groups in Iraq and Syria.

French officials say the measure will increasingly be implemented after President Francois Hollande's Socialist government unveiled new security measures earlier this year following two attacks in Paris by Islamist militants which killed 17 people and the three attackers.

"I have informed the Prime Minister of the decision to strip five nationalities of terrorists and I will continue this policy with the utmost determination," Interior Minister Bernard Cazeneuve told lawmakers.

An interior ministry source said the five included four Moroccans and a Turk. The five were arrested in 2004 and 2005 and have now served their sentences. They are still entitled to appeal the decision which, if it is upheld, could lead to their expulsion.

The five were originally sentenced for belonging to a France-based logistics cell of the Moroccan Islamic Combatant Group which carried out the May 16, 2003 attacks on the Moroccan city of Casablanca.

Officials did not specifically say why the interior ministry had decided to strip the five of French citizenship.

A Franco-Moroccan, Ahmed Sahnouni el-Yaacoubi, naturalised in 2003, was expelled on Sept. 22 after he failed in an appeal against a decision to strip him of his nationality following convictions in 2013 for conspiracy to commit terrorist acts.

While the law allows for a naturalised person to be stripped of their French passport if convicted on terrorism charges, the measure has only been used on eight occasions since 1998, according to a lawmaker.

(Reporting by Chine Labbe; writing by John Irish; editing by Michel Rose and Richard Balmforth) ((john.irish@thomsonreuters.com; 0033-1 49 49 53 42; Reuters Messaging: john.irish.thomsonreuters.com@reuters.net))

Keywords: FRANCE TERRORISM/NATIONALITY