Customs revenues plummeted due to the global economic crisis and a drop in South African imports.

FORBES: Swaziland

Turkey's interior, justice and customs ministers were due to fly to the area to be briefed on the incident.

BBC: Syria crisis: 'Powerful' minibus explosion kills 13

But more than 50% of its trade is within Europe, partly due to a customs union that has been in effect since 1995.

BBC: Turkey's inflation woes

The e-mails, claiming to be from the Revenue and Customs, tell the recipient they are due a tax refund.

BBC: Tax form

Lord Sassoon told peers Her Majesty's Revenue and Customs collected more than 90% of the taxes due, but acknowledged it needed to do better.

BBC: Tax avoidance debate

He said Revenue and Customs would never send an e-mail to anyone saying that they are due a refund, but would instead contact them in writing.

BBC: Tax form