Underground tunnels in the Gaza Strip are the only way for millions of dollars worth of essential supplies to get past Israel's siege of the coastal territory.

But it has now emerged that at least 40,000 Gazans have lost their life savings in a scheme that promised up to 50 per cent profits in return for an investment in tunnel trading.

Hamas, which has de facto control of Gaza, returned a fraction of the $100m that disappeared through the scheme, and has said that is investigating the fraud.

However, with hundreds of middlemen as yet unpunished and many of them rumoured to have had links to Hamas, the duped Gazans say that more should be done.

Al Jazeera's Zeina Awad reports from Gaza.