BEIJING, July 25 -- Prosecutors investigated more than 25,000 people on suspicion of corruption in the first half of 2014, according to statistics released by the Supreme People's Procuratorate (SPP) on Friday.

About a quarter of them, or more than 6,300, are functionaries, a SPP official said at a press conference. The figure represents a year-on-year increase of 14 percent, he said.

After the 18th National Congress of the Communist Party of China in late 2012, China launched an anti-graft campaign targeting both "tigers and flies," referring to high- and low-ranking corrupt officials.

The SPP said nearly 1,680 officials at or above county level were investigated in the first six months, registering an increase of 32.3 percent.

In the same period, the number of "major cases" with bribery amounts exceeding 50,000 yuan (about 8,118 U.S. dollars) and embezzlement surpassing 100,000 yuan, reached about 16,000, or nearly 84 percent of the total. The number of major cases increased 13.7 percent compared with last year.

Xu Jinhui, chief of the SPP's anti-graft bureau, said prosecutors had tightened their crackdown on the practice of offering bribes while also dealing with those taking bribes.

About 4,400 people were probed for offering bribes, a year-on-year increase of about 38 percent, according to the SPP.

Xu vowed to retrieve illegal gains from officials who have fled China.

The SPP will set up a leading work group to retrieve bribery funds from overseas, enhance its supervision over major cases, and build a database of information about fugitive officials.

From January to June, 320 suspects involved in corruption cases were seized and brought back to China, according to the SPP.