* Zuma criticised for "excessive" $23 mln home upgrade
* President denies wrongdoing, awaits further report
* Ruling ANC expected to win in May 7 election (Recasts with opposition reaction)
By Wendell Roelf
CAPE TOWN, April 3 (Reuters) - South Africa's main opposition party accused President Jacob Zuma on Thursday of trying to "run away" from explaining his role in a $23 million state-funded security upgrade to his home that was heavily criticised by anti-corruption investigators.
Public Protector Thuli Madonsela, South Africa's top graft watchdog, said in a report last month Zuma should pay back some of the money spent on upgrades to his Nkandla home, which included a chicken run and swimming pool.
Madonsela described the spending as excessive and accused Zuma of conduct "inconsistent with his office" but he has since denied any wrongdoing, arguing he was unaware of many of the upgrades and did not ask for them.
Zuma met a Wednesday deadline for him to respond to parliament but said that before he acted he wanted to see the findings of a separate probe by the police's elite Special Investigating Unit (SIU) that he ordered in December.
The opposition Democratic Alliance (DA) said this was merely stone-walling until after a May 7 election.
"The reality is that President Zuma is trying to run away from accountability and delay having to explain his actions to South Africa until after the elections," DA parliamentary leader Lindiwe Mazibuko said in a statement.
Zuma has been pilloried over the Nkandla scandal, including by senior members within the ruling African National Congress (ANC). Despite the outrage, the ANC is widely expected to win the election, giving Zuma another five years in office.
"I am intent on giving full and proper consideration to all these matters," he said in a statement released on Thursday.
"Upon receipt of the SIU report I will provide parliament with a further final report on the decisive executive interventions which I consider would be appropriate."
His response has only succeeded in angering critics who say corruption has worsened under Zuma and is undermining the popularity of the ANC, which has ruled South Africa since the end of apartheid in 1994.
It is also a key concern for investors in Africa's largest economy.
"In a healthy society, wrongdoers accept the consequences of their actions," Mavuso Msimang, a senior ANC member and former interior ministry director general, wrote in an editorial in the Business Day newspaper.
"We in the ANC owe it to the people of South Africa to repudiate corruption. We owe it to ourselves as a movement to put a stop to the cancer that causes power to be abused," he added.
Zuma, a polygamous Zulu traditionalist with no formal education, has been beset by scandal throughout his political career. He managed to avoid being tried for corruption in 2009 when the state withdrew its case on a technicality. (Editing by Joe Brock and Ed Cropley)