American diplomats have voiced concern over China's execution of a Tibetan man and the death sentence given to a monk for bomb attacks allegedly in support of Tibetan independence. American officials worry the Tibetans did not receive a fair trial. A U.S. embassy spokesman in Beijing said Tuesday he "joins the international community in raising concerns" over the execution of Lobsang Dhondup and the suspended death sentence imposed on Tenzin Deleg Rinpoche.

Court officials in China's Sichuan Province say Lobsang Dhondup was executed on Sunday. The court also rejected the appeal of a suspended death sentence by senior Buddhist monk Tenzin Deleg Rinpoche. Such sentences are likely to be commuted to life imprisonment.

The two Tibetan men were charged with setting off a string of bombs over the past two years in an area of Sichuan Province that is heavily populated with ethnic Tibetans. China says the bombs were meant to promote Tibetan independence, and killed one person and injured others.

But the U.S. spokesman says his embassy has "repeatedly registered deep concerns over the lack of transparency and apparent lack of due process" in the case of the two Tibetans. He adds that China denied an American request to let an observer attend the trial.

At a news conference Tuesday, Chinese Foreign Ministry Spokeswoman Zhang Qiyue responded, arguing that any country would punish criminals who undermine public security or carry out terrorist bombings. She also defends China's judicial system, saying that the country has strict reviews of all capital punishment cases.

Since People's Liberation Army troops imposed Communist rule over Tibet in 1950, the Himalayan region has been hit by sporadic violence in support of Tibetan independence.

Human rights groups say Lobsang Dhondup's case is the first known execution of a Tibetan for alleged political offences in many years. The groups say at least 10 other Tibetans have been detained in connection with the case, and several have reportedly been tortured or mistreated by police.