The bishops of South Africa have called on the country's embattled president, Jacob Zuma, to consider stepping down as part of an effort to fight corruption.

Marches protesting Zuma have been held across cities in South Africa after he reshuffled his cabinet, replacing a respected finance minister at the end of March, which resulted in the country's credit rating being cut to junk status by S&P.

The sacked minister, Pravin Gordhan, is regarded as an opponent of government corruption.

"We respectfully remind President Zuma that he has been elected to serve all South Africans," read the April 4 letter from the South African bishops' conference, signed by Archbishop Stephen Brislin of Cape Town.

"It appears that he has lost the confidence of many of his own closest colleagues, as well as that of numerous civil society organisations. He should earnestly reconsider his position, and not be afraid to act with courage and humility in the nation's best interests."

However, the bishops' letter also noted that while they "noted and respect" the calls for Zuma to resign, "such as step would not in itself be a complete solution, as corruption at every level must to be rooted out."

Zuma has been South Africa's president since 2009, and his term of office is not due to end until 2019. He is also leader of the African National Congress, which has ruled the country since 1994.

Though some elements in the ANC, as well as several of its allied parties, are calling on Zuma to resign, the party's National Working Committee has reiterated its support for him.

In their April 4 statement, the bishops wrote that "the leadership of the ANC must make serious and strenuous efforts to end corruption and patronage at all levels of governance."

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"In the present state of anxiety and uncertainty it is of utmost importance that Parliament be reconvened urgently. There is an enormous obligation on our public representatives … to exercise their duty of holding the Executive arm of government to account."

"We hope that Membersof Parliament will be guided by the welfare of our country and its people, and not by narrow loyalties or factional interests," they added.

The bishops concluded by stating: "We have confidence in the leaders of the two noble institutions, Parliament and the ANC, and we trust that they will rise to the occasion and give decisive, fearless and honest leadership."