Bahrain this week sentenced eight activists and opposition leaders to life behind bars and 13 other to various jail terms after they were convicted of plotting to overthrow the Sunni government.
U.N. Secretary-General Ban Ki-moon in a statement through his spokesman expressed "deep concern" over the harsh prison sentences handed down against the 21 opposition figures.
Ban called on Manama to "allow all defendants" to receive a fair trial and "do everything possible" to create a climate for concrete national dialogue.
Washington, which was criticized for taking a soft issue on the matter, questioned how Manama can call for dialogue while members of the opposition are in jail. Bahrain hosts the U.S. Navy's Fifth Fleet.
Shiite resistance movement Hezbollah in a statement through its al-Manar news station echoed Washington's sentiments, saying the Sunni monarchy was hypocritical in its official response to the Shiite uprising.
"This move confirms the regime's lies and claims that it is seeking dialogue," the statement read.