Chinese Prime Minister Wen Jiabao Friday pledged religious freedom and cultural protection in Tibet, just hours after security forces reportedly killed two Tibetans who protested China's rule.

"We will place more importance on improving the lives of our Tibetan compatriots, on protecting the... traditions of Tibet... and in preserving the freedom of religious belief of Tibetans," Wen said.

Wen's comments come after US-based broadcaster Radio Free Asia (RFA) said security forces shot dead two Tibetan brothers who were on the run after protesting against Chinese rule.

The killings came a day after a monk reportedly set himself alight.

The incidents are said to have taken place in two provinces bordering the Tibet autonomous region, as tension in Tibetan-inhabited areas intensified over perceived religious, political and cultural repression.

China launched a clampdown after at least two other Tibetans were killed in a series of protests last month, in what Beijing says is a battle against forces trying to split Tibet from the rest of China.

Wen further urged the Panchen Lama, a top Tibetan Buddhist leader selected and educated by communist authorities, to use his influence to instil patriotism among Tibetans, the government said in a report on its website.

"We hope you can guide the monks and the (Tibetan) people to love the country, uphold the law and follow Buddhist practice... you should play an important and active role in safeguarding national and ethnic unity," he told the Panchen Lama.

According to RFA -- a US-funded group that broadcasts news in several languages including Tibetan -- Yeshe Rigsal, a monk, and his brother were shot dead Thursday in the southwestern province of Sichuan.

The duo had taken part in a protest in the predominantly Tibetan Luhuo county on January 23 that turned violent when police shot dead at least one person. Two other areas of western Sichuan were then also hit by unrest.

China has blamed much of the unrest on the Dalai Lama, Tibet's exiled spiritual leader. Chen Quanguo -- head of the Tibet autonomous region -- said Thursday the fight against the Nobel Peace Prize laureate would be tough.

"Our struggle against the Dalai clique is long, complicated and at times even acute," he was quoted as saying by the state-run Tibet Daily.

News of the latest shooting is very difficult to confirm after police locked down western Sichuan, barring foreign reporters from going and cutting most means of communication.

Calls made to Luhuo police and to a local monastery were met with a rapid beeping tone, suggesting phones had been disabled. A man at the government office said he was unaware of the incident.

RFA, citing a monk in India who has contacts in the region, said the two brothers had been on the run for more than two weeks and were hiding in the hills in a nomad region when they were found.

"Chinese security forces encircled the place where he (Yeshe Rigsal) was staying and shot him and his brother," a monk at Drepung monastery in India was quoted as saying, citing sources in the region.

The reported incident came a day after a monk in his thirties in Qinghai -- another province with large populations of ethnic Tibetans -- set himself alight, rights group Free Tibet and RFA said.

Calls to the government and police in Chenduo county, where the self-immolation reportedly took place, went unanswered.

This brings to at least 18 the number of people who have set themselves on fire in the past year in Tibetan-inhabited areas in protest at Chinese rule.

RFA and rights groups say another three Tibetans self-immolated a week ago in a remote village of Sichuan. However, local authorities quoted in the official Global Times newspaper have denied this.