Ramallah, West Bank - Security forces of the rival Palestinian governments routinely use torture and arbitrary arrests, among other tactics, to quash dissent by peaceful activists and political rivals, Human Rights Watch said Tuesday.

The charges come in a new report released by the New York_based watchdog, following a two_year investigation that included interviews with nearly 150 people, many of them ex_detainees. It accused both the Western_backed Palestinian National Authority in the West Bank and Hamas in Gaza of using “machineries of repression” to stifle criticism.

Human Rights Watch also said the systematic use of torture could amount to a crime against humanity under the United Nations’ Convention against Torture, and called on countries that provide funding to Palestinian law enforcement to suspend their assistance.

Palestinian President Mahmoud Abbas’ government joined the convention after Palestine was accepted as a nonmember state at the UN.

“Palestinian authorities have gained only limited power in the West Bank and Gaza, but yet, where they have autonomy, they have developed parallel police states,” said Tom Porteous, deputy programme director at Human Rights Watch. “Calls by Palestinian officials to safeguard Palestinian rights ring hollow as they crush dissent.”

According to HRW, the Palestinian leaderships in the West Bank and Gaza engage in similar tactics, in most cases without holding anyone to account.

Among the alleged abuses: whipping people’s feet, forcing detainees into painful stress positions, hoisting up people’s arms behind their backs with rope and coercing suspects into granting access to their mobile phones and social media accounts.

Both Hamas and the Fatah_led PNA denied the accusations.

The two Palestinian factions split in 2007 after Hamas violently seized the Gaza Strip from forces loyal to Abbas. For more than a decade, Hamas has maintained an iron grip on power and suppressed any signs of public dissent, including street protests and on social media.

Despite having Western backing, Abbas has also silenced dissent in the areas of the West Bank he administers under past agreements with Israel. Last year, he clamped down on social media and news websites with a vaguely worded decree that critics say allows his government to jail anyone on charges of harming “national unity” or the “social fabric.”

Abbas’ security forces also work closely with Israel to keep Hamas in check in the West Bank. Critics accuse Israel of holding Palestinian detainees without charge for extended periods and also of torture.