The Congress of South African Trade Unions (Cosatu) is the "main block" on the road to job creation and redress for millions of South Africans, Democratic Alliance (DA) leader Helen Zille said yesterday, in the latest among a series of attacks that have come to define relations between the party and the unions.

Clearly irritated by Cosatu’s refusal to participate in the Western Cape government’s Economic Development Partnership, Ms Zille accused its general secretary, Zwelinzima Vavi, of using the federation to build a personal power base for himself.

Ms Zille said in a speech to students at the University of Stellenbosch yesterday Mr Vavi would attempt to "capture" the tripartite alliance at the African National Congress’s (ANC’s) 2017 conference. She said it was time South Africans saw through Cosatu, which wanted to "keep unemployed people excluded from jobs and economic opportunities, to protect its power base".

The Economic Development Partnership seeks to "bring together all stakeholders in (the provincial) economy across all sectors to create a joint vision for the Western Cape’s economic future and to facilitate innovative approaches to job creation," Ms Zille said.

Her comments echoed DA parliamentary leader Lindiwe Mazibuko’s attack on Mr Vavi this month, in an article where she questioned Cosatu’s opposition to the Protection of State Information Bill.

The DA also appears to be positioning itself as a party that speaks for the poor, in a bid to win more votes from the black majority in the 2014 national elections.

Political analyst Terry Bell yesterday said the DA was "not favourably inclined towards radical trade unionism", which had become Cosatu’s preferred stance on several economic and labour issues.

Mr Bell also said the DA would be concerned with Cosatu’s "emergence (as) a more social democratic left alternative to the ANC".

Ms Zille challenged Mr Vavi to split from the alliance and run for elections. "If he wants to run this country, then he should put his name on the ballot and stand for election," she said.

However, Mr Bell said Mr Vavi "does not strike one as necessarily ambitious, but he may well be".

"He has been given the opportunity (to lead) before and he has not taken it," he said.

Ms Zille also said Cosatu’s rejection of a more flexible and responsive labour market and the proposed youth subsidy was not in the best interests of the poor.

"The truth is that (Mr) Vavi and Cosatu are just doing what trade unions do best - protecting their members, who are all employed and are working their way up the economic ladder. Its animating purpose is solely to protect its own members’ interests," she said. "It is now clear (President Jacob) Zuma’s government is in office, but it is not in power.... Cosatu exercises a veto over government policy in education, labour and economic reform."

Presidency spokesman Mac Maharaj said Ms Zille’s comments where unfounded and belonged to a "political soapbox arena".

Cosatu said it "rejects with utter contempt the ludicrous and defamatory accusation" made by Ms Zille. "Her outburst is motivated purely by envy at Cosatu’s ability to mobilise millions of South Africans of all races in its campaigns, something which she knows she can never do," spokesman Patrick Craven said.

"It confirms everything we have been saying about the DA’s right-wing, pro-rich and pro-business agenda," he said.