Police has started the investigation on severe beating of 16 nuns in China, after international groups voiced concern over the issue.

It has been almost 20 days since the brutal attack happened in Xian City of the Shanxi Province. 16 nuns of the Congregation of the Franciscan Sacred Heart Missionaries were reportedly injured, after a group of 40 young thugs repeatedly beat them on the night of Nov. 23. The local public security authorities have begun probing into the incident, according to the Monday edition of the Italy-based Catholic news agency AsiaNews.

In addition, the government announced that the Education Department would take charge of all medical expenses for all the nuns several days ago.

China has showed reluctance to reveal the persecution in public. A Chinese Catholic website that gave a detailed report of the incident was found to be closed, even after the site had reopened, the news was no longer available, AsiaNews reported.

Nevertheless, the coverage of foreign press has drawn huge international concerns and probably led to the reaction of the Chinese government. Particularly, the chairman of the United States Conference of Catholic Bishops’ Committee (USCCB) on International Policy demanded the Chinese government for a full investigation, according to a letter to the Chinese Embassy in Washington D.C.

"…this barbaric behavior calls for a thorough investigation and appropriate sanctions against those responsible," the letter posted on USCCB website read.

"Government offers to pay for part of the hospital expenses incurred is implicit acknowledgement of official involvement in the attack and is a thoroughly inadequate response," it added.

In the letter, Bishop Thomas G. Wenski of Orlando lamented that the Chinese embassy has repeatedly failed to respond the Bishops’ Conference regarding three previous reported violations of religious liberty in China.

The Vatican has also issued a statement condemning the attack and has expressed worry because "the authorities had not yet provided an explanation for their arrest."

Furthermore, the All India Catholic Union (AICU), the largest and oldest organization of lay Catholics in Asia called on the United Nations, international groups, and the Indian government to take actions so that "Beijing understand such actions against freedom of worship do not behoove a great nation like China seeking global recognition in the economic sphere."

The attack on the nuns was triggered by a land dispute between the convent and the authorities. The building where the attack occurred was actually the location of the "School of the Rosary," an elementary school run by the nuns but belongs to the state since the Cultural Revolution.

Most recently, the city government sold the building to a company that wants to demolish it to build industrial units and other buildings. Some 200 nuns therefore have been staging a sit-in protest in the building for several days to protect it from being demolished. The attack took place when some nuns were trying to defend the building from being destroyed by officials.

Meanwhile, five nuns have remained hospitalized since the beginning because of serious injuries. According to AsiaNews, Sr Dong Jianian, age 41, suffered a fraction to her spinal column and has been recovering after a three-hour operation. However, the 34-year-old Sr Cheng Jing was blinded in one eye. The other three are in severe conditions as well.