DUBAI, United Arab Emirates—Al-Jazeera says hackers have targeted the Qatar-based TV satellite channel for the second time in a week, sending out false news reports on its mobile phone alert service.

A pro-Damascus group known as the Syrian Electronic Army quickly claimed responsibility for the Sunday hack on Twitter. Qatar is a harsh critic of the Syrian regime and a leading backer of the rebels.

The inaccurate texts sent included a claim that the Qatari prime minister had escaped an assassination attempt. A spokesman says an investigation is ongoing.

Hackers posted a pro-Syrian statement on Al-Jazeera's website last week.