Zimbabwe cranked up the face value of its highest banknote fivefold on Thursday as black-market trading in scarce gasoline and hard currency spiralled. On the illegal market, a single United States dollar bought up to Z$8 000, up from Z$5 000 last month.

Store shelves normally stocked with staples such as corn meal, cooking oil and sugar were empty on Tuesday as the Zimbabwe government threatened to take over manufacturers and retailers who failed to slash prices by half. Smaller shops shut down after running out of stock.

In Zimbabwe's capital and in need of a bath or a hot meal? Call a friend, though it'll likely take several attempts to get through. Power and water outages have revived friendships and socialising in Zimbabwe, homeowners say. People see more of each other during outages that last several days, says businessman James Martin.

In this nation that once boasted one of sub-Saharan Africa's most vibrant economies, things have become so bad that people have taken to telling a wry joke: "What did we have before candles?" The answer: "Electricity." Four years of turmoil have turned back the clock here. Ambulances are drawn by oxen. Hand-guided cattle plows have replaced farm machinery.

A militant Zimbabwean youth group is calling for a boycott of Nando's, whose latest ad depicts President Mugabe as a lonely "last dictator standing".

Zimbabwe's president vowed on Friday to avenge Western economic curbs imposed on his ruling party.

A top research group on Thursday rated Zimbabwe's capital as the worst of 140 world cities in which to live but this study excluded war zones.

President Robert Mugabe says elections will "definitely" happen this year, calling politicians who say polls should be held in 2013 "cowards".