BEIJING (Reuters) - The number of corruption cases heard by Chinese courts jumped by about one-third last year, as the country’s top prosecutor vowed on Sunday there would be no let up in China’s campaign against deep-seated graft.

Since assuming office more than four years ago, President Xi Jinping has waged war on corruption, warning, like others before him, that the problem is so bad it could affect the ruling Communist Party’s grip on power.

Dozens of senior figures have been jailed for corruption and abusing their positions, including a once powerful domestic security chief, Zhou Yongkang.

In an annual report to China’s largely rubber-stamp parliament, chief justice Zhou Qiang said Chinese courts in 2016 heard 45,000 graft cases involving 63,000 people, though he did not say how many had been convicted or provide a comparison.

Compared with figures he gave in last year’s report though, that represents about a one-third rise for both on 2015.

Top prosecutor Cao Jianming said in his work report that anti-corruption efforts will “absolutely not weaken”.

“The zero-tolerance stance on corruption will certainly not be changed,” Cao said.

Both men also promised to keep up the pressure on separatists, extremists and terrorists.

However, they provided no details on the number of people convicted for these crimes in 2016.

In 2015, Chinese courts convicted more than 1,400 people for harming national security, including taking part in terrorism and secessionist activities, double a broadly equivalent number given for 2014.

Hundreds of people have been killed over the past few years in China’s resource-rich Xinjiang province, strategically located on the borders of central Asia, in violence between the Muslim Uighur people, who call the region home, and ethnic majority Han Chinese.

Officials have blamed the unrest on Islamist militants and separatists, though rights groups and exiles say anger at Chinese controls on the religion and culture of the Uighurs is more to blame for the strife. China denies any repression in Xinjiang.