A former Khmer Rouge prison chief will appeal a sentence for war crimes that some Cambodians have already denounced as too lenient.

A spokesman for the international tribunal that sentenced Kaing Guek Eav, also known as Duch, said Tuesday a lawyer for the convicted torturer has given formal notice of his intention to appeal.

Duch was found guilty of war crimes and crimes against humanity while he served as chief of a notorious prison in the late 1970s.  Relatives of some of his victims broke into tears of anger on Monday when the tribunal announced he would serve only 19 years in prison for his crimes.

Duch is the first senior Khmer Rouge official to face trial more than three decades after some 1.7 million people died at the hands of the brutal regime.

Surya Subedi, the United Nations human rights expert on Cambodia, said the ruling represents a historic milestone in holding those responsible for human rights violations accountable.

But some survivors and victims' families complained the sentence had undermined their confidence in the U.N.-backed tribunal, which included foreign judges.  The court reduced the sentence from 35 years to 19, citing time served and other mitigating factors.  Duch has been jailed since 1999.

He has confessed to having committed crimes as a chief warden in Tuol Sleng prison, including torture and overseeing the mass murder of at least 14,000 people.   

Duch is one of five Khmer Rouge leaders being tried by the special tribunal.  The other four, who are accused of genocide, were part of Khmer Rouge leader Pol Pot's inner circle.  They are expected to appear in court later this year or early in 2011.  Pol Pot died in 1998.

The Khmer Rouge regime ended when Vietnamese troops invaded Cambodia in 1979.

Some information for this report was provided by AP, AFP and Reuters.