On Thursday, The New York Times (NYSE:NYT) said that hackers from China had breached its computer systems in a series of attacks. The hackers obtained employee passwords and gained access to data files, the Associated Press noted.

The hacking began around the time the newspaper began looking at the means by which the family of Chinese Premier Wen Jiabao amassed $2 billion in assets. Hackers installed viruses on U.S. university computers to channel the attacks and used tactics similar to those used by Chinese military hackers who have launched cyber attacks on U.S. defense companies.

The personal computers of 53 Times employees were hacked. However, the newspaper insists that the hackers did not access any customer data. Nor did they access any of the Times‘ research into Wen family fortune.

China dismissed the newspaper’s allegations and noted that hacking was against Chinese law.

In October, the U.S. House of Representatives Intelligence Committee issued a report warning that the Chinese military could plant software in products made by prominent Chinese electronics manufacturers allowing it to spy on U.S. businesses and government agencies.

Shares of the New York Times Company rose about 1% in Thursday morning trading.