Police officers drag away a Tibetan monk while he attempts to nurse an injured fellow monk in Katmandu, Nepal, 25 Mar 2008

A top Chinese official has ordered security forces in Tibet to remain on alert for further unrest, as authorities have announced the arrest of 13 people allegedly involved in recent protests in the capital, Lhasa.

State-run media say 13 people were arrested Monday in China's crackdown on the protests. Authorities issued arrest warrants Tuesday for an additional 29 accused of involvement in the peaceful protests that turned violent.

During a visit to Lhasa, China's minister for public security, Meng Jianzhu, said the government will step up its so-called "patriotic education" campaigns at Buddhist monasteries in Tibet. Meng headed a delegation of Chinese officials on a tour of Tibet Sunday and Monday.

During a stop at the Jokhang temple, Tibet's most sacred shrine, and, Sera and Drepung, site of the March 14 protests, Meng chided monks for undermining what he called national solidarity. He accused those who participated in the riots of violating the doctrines of Tibetan Buddhism.

Meng's visit comes after a fresh protest in Tibetan parts of western China Monday left at least one policeman and one monk dead.

China says about 20 civilians were killed in all of the unrest, while Tibetan exile groups put the toll at about 140.

China has banned foreign journalists from traveling to the region, so details of the protests and security crackdown are difficult to verify.

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