Two Eritrean opposition journalists in Sudan have been detained by Khartoum\'s intelligence service, an Eritrean opposition source said on Tuesday. Abdalal Mahmoud of the Eritrean Centre for Media Services (www.adoulis.com) and Haroun Adam, who has also written for the foreign-based opposition website, have been held since Monday, according to the Khartoum-based opposition source. Eritrean opposition groups are banned in neighbouring Sudan. Agents called both writers to report to the security office on Monday but neither has returned and their phones are off, the source said, asking for anonymity. French-based watchdog Reporters Without Borders (RSF) ranks Eritrea last of 179 countries on its 2011-12 Press Freedom Index. Sudan fares little better, at 170