TUNIS, Sept 20 (Reuters) - Tunisia's anti-terrorism police detained for one day Ali Laarayedh, a former prime minister and senior official in the Islamist opposition Ennahda party, after an investigation into suspicions of sending jihadists to Syria, his lawyer said on Tuesday.

In the same case, the police postponed the hearing of Tunisia's Islamist opposition leader and speaker of the dissolved parliament Rached Ghannouch to midday on Tuesday, after waiting for about 14 hours.

It is expected that Laarayedh will appear before a judge on Wednesday, the lawyer Mokthar Jmayi told Reuters. (Reporting by Tarek Amara; Editing by Kim COghill)