WASHINGTON — The United States said Tuesday it was "seriously concerned" by reports of deadly clashes in Tibetan regions of China, where police are accused of opening fire on peaceful protesters.

"We urge the Chinese government to engage in a constructive dialogue with the Dalai Lama or his representatives as a means to address Tibetan concerns," State Department spokeswoman Victoria Nuland told reporters in Washington.

China on Tuesday accused "overseas secessionist groups" of trying to discredit the government after the clash in a Tibetan-inhabited area saw injured locals taking refuge in a monastery.

According to the London-based Free Tibet advocacy group and local monks, police opened fire on Tibetans protesting against religious repression in the southwestern province of Sichuan on Monday, killing at least one and injuring more than 30.

But China's foreign ministry said Tuesday their account of the incident in Luhuo county was hyped, and that a mob stormed stores and a police station, prompting a clash in which one protester died and five officers were injured.

The unrest comes at a sensitive time in Tibetan-inhabited areas, where at least 16 people have set fire to themselves in less than a year -- including four this month alone.

Accounts of Monday's death toll vary. The monks and Chinese government say one person died, but a man at a local hotel said he heard three people had been killed, as did the US-based International Campaign for Tibet (ICT).

The India-based Tibetan government-in-exile, meanwhile, said the death toll could be as high as six.