By Paul Day
MADRID (Reuters) - The Spanish government is considering cracking down on hate speech on social networks after thousands of anti-Semitic comments on Twitter following an Israel-Spain basketball game on Sunday.
Jewish groups filed a legal complaint on Tuesday calling for official action against tweeters who made gas chamber and Holocaust comments after Maccabi Tel Aviv basketball team defeated Spain's Real Madrid in the Euro League final.
State prosecutors are looking into the complaint against users of an obscene Twitter tag, which the Jewish groups say became a trending topic on Twitter in Spain after over 4,000 direct messages on the microblogging network, and thousands more retweets.
The anti-Semitic posts are embarrassing for a country which recently approved a law allowing descendents of Sephardic Jews expelled from the country in 1492 to seek Spanish nationality.
On Sunday, the village of Castrillo Matajudios in northern Spain will on whether to change its name - which means Kill the Jews Fort - and purge a vestige of anti-semitism stemming from the days of the Inquisition.
Justice and interior ministry officials met with a senior state prosecutor on Monday to discuss how Spanish law can cope with defamatory, racist or discriminatory speech on social networks, a source at the justice ministry said.
"It's not about writing new laws. Within Spanish law this behavior is already penalized. It's to evaluate Twitter as a new variable within this law," said another source close to the talks.
Both government sources spoke on condition they not be named, citing ministry rules.
Spain is grappling with a spate of incendiary tweeting, especially following the murder of Isabel Carrasco, a leader of the conservative People's Party (PP) and president of the county council of Leon in northern Spain.
Four people have been charged with apologia - sympathizing with a criminal act - after sending tweets that police say celebrated Carrasco's death. She was shot dead May 12 while walking through the city of Leon.
Under Spanish law, successful prosecutions could carry prison sentences of up to two years.
They have also provoked debate on how far the law should be permitted to censor comments made on social networks after Interior Minister Jose Fernandez Diaz said they must purge undesirables from social media.
"There are comments on the internet which can be considered unfortunate, a symptom of bad manners or in bad taste, but that doesn't mean they should be met with a legal response," said Joaquim Bosch, spokesman for Judges for Democracy, an association of judges and magistrates.
"We need to differentiate between stupid comments where people are letting off steam and real threats."
In April, 17 people were arrested for comments on social media which either glorified illegal groups such as the violent Basque separatist group ETA or Jihadists, or insulted their victims.
A source from Spain's Civil Guard - the national gendarmerie force - said those arrests were part of a police effort called Operation Spider but was unable to say whether charges had been brought.
(Editing by Fiona Ortiz and Angus MacSwan,)