HARARE, Zimbabwe's President Robert Mugabe turns 93 Tuesday and has declared that he is ready to soldier on as head of state and government.

Mugabe, who is Africa's third longest-serving leader after Jose Eduardo dos Santos of Angola and Teodoro Obiang Nguema Mbasogo of Equatorial Guinea, is the only head of government Zimbabweans have ever known since the country attained independence from Britain in 1980.

In an interview with State television to be aired this week, Mugabe said he would only step down if the call came from his ruling Zanu PF party, but that would not be any time soon because the party wanted him to stand as its candidate in the 2018 elections when his current tenure ends.

"They want me to stand for elections everywhere in the party," Mugabe said, adding that in any case party members did not consider anyone good enough to replace him at the moment.

His sentiments echoed those of his wife Grace who said on Friday that even if Mugabe was to contest the election as a corpse, the people would still vote for him.

Mugabe introduced universal education and a robust social programme which saw previously marginalized communities benefiting while international aid organizations poured in millions in support of the fledgling government.

However, relations with Western powers started getting frosty over perceived misgovernance issues and alleged violation of human rights in the 1990s and eventually broke down in 2000 when the government expropriated land from white commercial farmers and re-allocated it to formerly landless blacks.

This led to serious economic decline with Mugabe attributing most of the failures to economic sanctions imposed on Zimbabwe by the European Union (EU), the United States and their Western allies since the early 2000s over the land issue.

The government also blames persistent droughts for the decline.

The World Bank said the country's economy grew by 0.4 per cent in 2016, weighed down by a drought and low commodity prices, the lowest growth since the country adopted a multi-currency regime in 2009.

The country recorded a trade deficit of 2.3 billion US dollars in 2016 because of low activity in the manufacturing sector, while Foreign Direct Investment (FDI) was curtailed by the government's hazy indigenization policy which favours blacks.

Zimbabwe has also been hit by cash shortages since 2014, with the US dollar -- the major currency in the multi-currency basket adopted in 2009 -- becoming elusive.

As a result, the Reserve Bank of Zimbabwe has introduced bond notes at par with the dollar to plug the deficit, but while many people have grudgingly accepted them, prices of some commodities continue to rise as the black market operators come into play.

Civil servants have endured the effects of a harsh economy with payments of their salaries being made late.

In the meantime, Mugabe's ruling Zanu-PF party has remained divided along factional lines over the years. Vice-President Emmerson Mnangagwa is the perceived leader of one faction going by the name Lacoste, while Mugabe's wife is fighting in her own corner with mainly younger leaders calling themselves Generation 40.

Both factions will converge in southern Zimbabwe on Saturday to celebrate Mugabe's birthday at a lavish party organized by the party's youth league.

Former vice-president Joice Mujuru was expelled from the party following the party's congress in 2014 for allegedly harbouring ambitions to topple Mugabe and has since formed her own political outfit.