(Adds comments from Iraqi journalists' rights group)

MOSUL, Iraq, May 4 (Reuters) - Gunmen shot dead an Iraqi reporter on Sunday after hauling her out of a taxi in Mosul, a notoriously violent city in northern Iraq where journalists are often targeted and live in fear of their lives.

Police said Serwa Abdul-Wahab, in her mid-30s, was on her way to work when gunmen forced her out of a taxi in east Mosul, 390 km (240 miles) north of Baghdad, and shot her in the head.

A colleague who declined to be named for fear of being attacked said she had received a text message on her phone three weeks earlier warning her to stop reporting or she'd be killed.

Yassir al-Hamadani, a friend of Abdul-Wahab's and the head of the Mosul branch of the Iraqi Association for Journalists' Rights, confirmed the police version of events.

"Abdul-Wahab worked with us and was an active defender of Iraqi journalists' rights. We're very sad to lose her," he said.

Police were not immediately able to say why anyone would want to target her. Fellow journalists said she was a contributor to www.muraslon.org, an Iraqi news website.

She also worked as a secretary for the electoral council, charged with preparing for Oct. 1 provincial elections.

Iraq, which witnessed significant growth in the media after the 2003 U.S.-led invasion, is the most dangerous place in the world for journalists to work, according to New York-based journalism watchdog the Committee to Protect Journalists (CPJ).

Iraqi journalists have been targeted because of their work or caught up in the cross-fire of Iraq's many-sided conflict.

The CPJ estimates that 127 journalists, both Iraqi and foreign, have been killed since 2003, not including Abdul-Wahab.

Gunmen killed the head of Iraq's biggest journalist organisation, Shihab al-Tamimi, 74, in Baghdad in February.

In all, three journalists have been killed this year, the CPJ said. A count by Reuters, however, puts the toll at five.

The CPJ said in a report last week that Iraq had the world's worst record of solving murders of journalists, with 79 unsolved.

Journalists in Mosul keep a low profile, fearful of attracting the attention of al Qaeda, which has threatened many media workers there with death. The U.S. military says Mosul is the last urban stronghold of the Sunni Islamist group. (Writing by Ross Colvin and Tim Cocks; Editing Jon Boyle)

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