BEIJING, Feb. 12 -- The central bank injected the most cash into the financial system in a year after a pre-holiday cash squeeze drove the benchmark overnight interbank rate to a five-week high.

The People's Bank of China (PBOC) pumped in 205 billion yuan (33.44 billion U.S. dollars) net this week, the largest amount since January 2014, in an effort to meet high cash demand before the week-long Lunar New Year holiday, which begins on Feb. 18.

Tight liquidity has been exacerbated by investors seeking funds for equity initial public offerings (IPO) subscription. A total of 24 IPOs are planned this week, which is expected to lock up 2.3 trillion yuan.

On Thursday, the central bank sold 80 billion yuan each of 14-day and 21-day reverse repurchase agreements (repos), a process in which central banks purchase securities from banks with an agreement to resell them.

The 14-day reverse repo was priced to yield 4.1 percent, while that of the 21-day reverse repo was 4.4 percent, according to a statement on the PBOC website.

In Thursday's interbank market, the benchmark overnight Shanghai Interbank Offered Rate (Shibor), which measures the cost at which Chinese banks lend to one other, climbed by 12.6 basis points to 3.058 percent, the highest since Jan. 6.