The dead bodies of two Hamas members were found on Wednesday in Syria's Husseinieh camp, the UK-based Syrian Observatory for Human Rights said on Wednesday.
According to activists, state security forces had executed the members of the Palestinian Islamist movement following their arrest, throwing their corpses near the camp-based Aisha mosque in a southern countryside area near Damascus.
Ismail Haniya, head of the Hamas government in Gaza, had offered his support to the Syrian opposition during its 21-month armed insurgency against the Assad regime, saying it was striving for "freedom, democracy and reform."
Such statement signified a shift in Hamas' previously neutral position regarding the complex political crisis in Syria.
Syria welcomed Hamas in 1999 after Jordanian authorities expelled the movement's leader-in-exile Khaled Meshaal.
At the time, a political alliance was built between Hamas and Damascus based on shared enmity to Israel. However, the situation changed after the Assad regime launched a crackdown on anti-government protesters in 2011.
Hamas, which is ideologically affiliated with Egypt's Muslim Brotherhood, distanced itself from Assad last year after the Damascus regime reportedly widened its crackdown to include Sunni Muslim protesters and rebels.
The Assad government consists largely of followers of the Alawite sect of Islam. Hamas, along with the Muslim Brotherhood of which it is an offshoot, is Sunni Muslim.
Brewing tensions between Damascus and the Hamas leadership led Meshaal to shut down the group's office in Damascus in February of last year and depart for Qatar, an oil-rich Gulf country that has supported the rebels fighting to topple Al-Assad.
Syria, in response, accused Meshaal of turning his back on Al-Assad, his one-time protector."Syria embraced Meshaal like an orphan looking for shelter after other countries shut the door in his face," AFP quoted a government commentator as saying on Syrian television last October.