When Avaaz put up hard-hitting ads in Johannesburg airport urging South African president Jacob Zuma to stop the trade in lion bone, the campaign got a speedy response.

Just not the kind we were looking for...

Bogus sex potions

More than 725,000 Avaaz members have so far signed the petition to ban the export of lion bone. The bones are used in bogus "sex potions" in Asia: meanwhile, wild lion populations are dwindling across Africa.

When the South African government did not respond, we thought we'd drive the point home at OR Tambo International Airport, the port of entry for millions of foreign tourists coming to enjoy South Africa's rich heritage of wildlife:

But within days of these powerful messages arriving to greet travellers, the billboards were taken down. Bureaucrats at the government-owned company that runs the airport, fearing that President Zuma's image on the billboards could cause "a public relations nightmare", ordered them removed.

See you in court!

The South African constitution protects exactly this kind of political expression. So now Avaaz is going to court to challenge the censoring of a message that nearly three-quarters of a million citizens want to send to Jacob Zuma.