The Syrian government released Wednesday 755 prisoners detained over the past nine months in the regime's crackdown on dissent as observers toured a flashpoint city to see whether authorities were complying with an Arab plan to stop the bloodshed that has killed thousands. The prisoners' release, reported by the state-run news agency SANA, followed accusations by Human Rights Watch that Syrian authorities were hiding hundreds of detainees from the observers now in the country. The New York-based group said the detainees have been transferred to off-limits military sites and urged the observers to insist on full access to all sites used for detention. HRW's report, issued late Tuesday, echoes charges made by Syrian opposition members that thousands of detainees were being transferred to military sites ahead of the observers' visit. Syrian officials have said the Arab League monitors will have unrestricted access to trouble spots but will not be allowed to visit sensitive military sites. “Syria has shown it will stop at nothing to undermine independent monitoring of its crackdown,” said Sarah Leah Whitson, Middle East director at Human Rights Watch. She said it was essential for the Arab League “to draw clear lines” regarding access to detainees, and be willing to speak out when those lines are crossed. The Arab observers kicked off their one month mission in the violence-wracked country with a visit on Tuesday to Homs — the first time Syria has allowed outside monitors to the city at the heart of the anti-government uprising. Meanwhile, The choice of a Sudanese general to head an Arab League mission in Syria has alarmed activists, who say Sudan's own defiance of a war crimes tribunal means the monitors are unlikely to recommend strong action against Syria's Bashar Al-Assad. The Arab League says Lieutenant-General Mustafa al-Dabi brings vital military and diplomatic expertise to its unprecedented mission to verify that Assad is complying with a deal to end Syria's crackdown on protesters. But some critics of Khartoum say it is all but impossible to imagine a Sudanese general ever recommending strong outside intervention, much less an international tribunal, to respond to human rights abuses in a fellow Arab state.