German election officials said on Monday they were investigating whether exit poll data were made public on Twitter before polls closed on Sunday and there might be an appeal against the result if laws had been broken.

We are currently investigating the facts of the case, said deputy electoral commissioner Uwe Korzen-Krueger in the eastern state of Saxony where the investigation was launched.

There were three state elections on Sunday in the run-up to the September 27 federal election: Saxony, Saarland and Thuringia. Chancellor Angela Merkel's conservatives looked set to hold onto power in Saxony but may be unseated in the two other states.

Korzen-Krueger said preliminary results -- that may or may not be based on exit poll data -- appeared on the Twitter social networking site about an hour before polling stations closed at 6 p.m. (1600 GMT) and could have influenced the vote's outcome.

An appeal against the election could be possible, he told Reuters.

The exit poll data, usually put together by private polling institutes, are often given to party leaders in the hours before the polls close.

Electoral commissioners are concerned the results of the federal election on September 27 could also be jeopardized if exit poll results are made public before polling stations close.

The premature publication of exit poll results is a breach of the law in all three states as well as on a federal level -- an offence which can be punished by a fine of up to 50,000 euros, the federal election office said on Monday.

Similar concern erupted after the re-election of conservative President Horst Koehler by the federal assembly in May, when some parliamentary deputies revealed the results of the vote on Twitter minutes before the official announcement.

Election officials in Saxony are still trying to find out whether the Twitter messages on Sunday were based on exit polls and whether to take legal action.

Korzen-Krueger said a Twitter account holder, a local politician for Merkel's conservatives, was exactly right with his forecast of the results in Saxony, where the conservatives look set to hold onto power -- as they do in the federal election on Sept 27.

(Editing by Tim Pearce)