Invitations are being sent to graduates of Tsinghua University - including President Hu Jintao - ahead of April's celebration of the famed institution's 100th birthday.

"We have sent the invitations to our alumni who have made achievements in their respective fields," said Shi Zongkai, vice-president of the university on Tuesday.

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Founded in 1911, Tsinghua University is considered to be one of the top universities in the country.

It has a prestigious alumni that includes political leaders, scientists and entrepreneurs.

Zhu Rongji, the former premier, is among graduates, as is President Hu Jintao, who graduated from the water conservancy engineering department in the mid-1960s.

As the days and weeks tick down to the celebration that will be held in the last week of April, alumni are donating money to help, said Shi, who expects this year's celebration to be the largest to date.

Meanwhile, members of the alumni are donating money to build the brand new "Tsinghua College".

Most of the donors are former students who studied after the end of the "cultural revolution" (1966-76) and have their own businesses, said Shi.

Construction work on the new building is scheduled to be completed before the anniversary and the new landmark will serve as a location for the hosting of public events in addition to being designed to accommodate around 2,000 students.

Shi said one former student donated 100 million yuan to the university in support of the project. He declined to reveal the donor's name.

According to a recent chart released on the China University Alumni Association's website, Tsinghua University and Peking University are the top two universities in terms of the number of billionaires among their alumni. It was reported that 70 billionaires graduated from Tsinghua.

At the same time, the "Old Tsinghua College" building, which was engulfed in flames in November is now in the midst of renovations. The front stonewall of the German-style building is intact but the roof had collapsed because of the fire and many walls were damaged.

The renovations will be finished in time for the centenary celebrations, Shi said.