Q+A-Why are S.Africa's Zuma's hands tied by labour?

JOHANNESBURG (Reuters) - A strike by 1.3 million workers in South Africa's public sector now in its 16th day is testing President Jacob Zuma and the ruling African National Congress's fragile relationship with organised labour.

Unions, especially the country's largest labour federation COSATU, were instrumental in propelling Zuma to the presidency but have become increasingly frustrated with his government's failure to adopt left-leaning polices they support.

This dissatisfaction could lead them to withdraw support for Zuma at the ruling party's mid-term policy conference later this month.

Below are some questions and answers about the extent to which Zuma is limited in his policies towards labour and the impact that worsening relations would have on the ANC's governing alliance with COSATU and the small but influential Communist Party.

CAN ZUMA GET TOUGH ON THE UNIONS?

Probably not. He will likely lose support from groups that helped him into power. Labour could also widen the strikes, undermining his presidency, damaging the economy and jeopardising votes for the ANC as it heads into nationwide elections for all local government posts next year.

The ANC has championed itself as the voice of the poor and disenfranchised and Zuma needs to be seen as furthering these ideals to build support in the party and to ensure it maintains its overwhelming strength at the polls.

Giving the unions the cold shoulder could spell political suicide.

CAN ZUMA FIRE WORKERS?

The government has the right to fire workers who defied a court order compelling essential employees such as nurses and court clerks to return to work, but it is not likely to do so. Despite a 25 percent unemployment rate, South Africa has a shortage of skilled labour. The government cannot afford to sack workers as it struggles to retain state employees who are lured by higher paid jobs in the private sector and abroad.

HOW MUCH DOES THE ANC NEED THE UNIONS

The two groups, who forged an alliance in the struggle to end apartheid, gain more from being together than they would likely gain from being apart.

COSATU, which has said the alliance is on the verge of rupture, does not have the finances or the widespread backing to form its own political party. Its main means to influence government policy is by ensuring a close relationship with the ANC, which effectively has enjoyed one-party rule since apartheid ended in 1994.

COSATU has demonstrated with the state workers' strike its enormous power to cause problems for the government and its potential to bring the economy to a halt. Its strong influence among workers has been a powerful tool for the ANC to mobilise voters.

In alienating COSATU, the ANC and especially Zuma risk losing support at the grassroots level, where millions still live in abject poverty in shanty towns and have benefited little from 16 years of democracy.

WHAT ARE THE RISKS TO THE ECONOMY?

The first risk from the close ties between the ANC and labour comes from above-inflation wage settlements paid to government workers and employees at state-owned enterprises that fan inflation, strain state finances and are used as benchmarks by unions in the private sector to seek higher wages too.

The next threat comes from preventing labour reforms to make the country more competitive among Brazil, India and the other BRIC emerging economies but have been opposed by unions.

Economists say South Africa's rigid labour laws -- favoured by unions -- make it difficult for employers to offer low wages and flexible employment to the country's poor. Labour reforms could ease the country's alarmingly high official 25 percent unemployment rate. The country's labour laws have been cited as a factor limiting foreign investment.

(Editing by Marius Bosch and Giles Elgood)