* IMF sees the rand as overvalued
* ANC's ties to labour limit labour reforms
* Youth League presses debate on nationalisation
(Adds quotes from delegate, labour leader)
By Jon Herskovitz
DURBAN, Sept 23 (Reuters) - South Africa's ruling African National Congress debated policies on Thursday to address a currency that is at 2-1/2-year highs and unemployment that affects at least one worker in four.
The group that enjoys virtual one-party rule in Africa's biggest economy has shied away from calls from left-leaning factions to drastically devalue the rand and also from taking the advice of economists who say it must add flexibility to a rigid and expensive labour market.
Delegates at a top-level, closed-door party meeting said debate on nationalising mines in the resource-rich country has been a heated topic of discussions.
The ANC's youth wing has called for nationalising mines, but ANC leaders said any policy on increased state ownership would not be made until at least 2012, when the party holds its next major meeting.
"The Youth League refused to back down on the their calls that nationalisation should be discussed, which caused a lot of tension in the committees," said an ANC member from Johannesburg who is attending the week-long conference.
The party's economic transformation commission will report later in the day on its findings to the plenary session of the ANC's National General Council, one of its biggest political events in years and where it adjusts its policy priorities.
President Jacob Zuma told the opening session on Monday he wanted to see a "stable and competitive" currency while a senior official said the party did not want to see any major swings in the rand.
The rand has been strengthened by foreign inflows into South Africa's relatively high yielding bonds and other assets as investors seek higher returns than they can get elsewhere.
The rand has gained almost 26 percent since the start of 2009 and it pierced the key 7.00 level to touch 6.98 on Wednesday, gains that will unsettle policymakers at the central bank and in government.
The International Monetary Fund on Tuesday said the rand could be overvalued by between 5 to 15 percent and reserves accumulation should continue.
"POLITICAL MEDALS"
The ANC, unlikely to want to antagonise governing partners such as union federation COSATU, is unlikely to adopt measures suggested by economists that would make it easier for employers to hire temporary workers or sack unproductive ones.
A top COSATU official reminded the ruling party that his organisation wants to have a say in policy formation.
"We have no doubt that the ANC, in recognition of the reality that we have political medals hanging round our necks but no economic jewellery, will take forward the pro-poor and pro-development ... resolutions," Secretary General Zwelinzima Vavi said at a union rally.
The ANC has called for "education, training, and skills development" to provide more job opportunities in South Africa where unemployment is running at around 25 percent.
Average wages in South Africa are about four times what city workers make in China and are much higher than in other developing countries, deterring investment. Frequent strikes have exacerbated the problem.
Relations between COSATU and the ANC have been strained by a strike through most of August by about 1.3 million state workers and complaints from the labour group about what it sees as growing cronyism in the government.
Zuma has tried to mend fences with COSATU at the meeting. He needs the help of its vote-gathering machine as South Africa heads into nationwide elections for all local posts in the first half of next year.
Eight ANC Commissions, including one proposing rules that would place new limits on the media, will report to the plenary on Thursday and their findings will be released on Friday. (Additional Reporting by Peroshni Govender; Editing by Giles Elgood)