A court in Italy's northern city of Milan is considering charges of corruption against Eni and Shell in a controversial oil deal that led to Nigeria losing an estimated $6bn (£4.7bn).

The deal gave Shell and Eni the rights to explore an offshore oil field in the Niger Delta which is estimated to contain nine billion barrels of oil.

But the process of how they secured the contract is dogged by claims of corruption.

Shell and Eni are accused of knowing the $1.1bn they paid to Nigeria would be used for bribes.

The Italian and Anglo-Dutch energy giants deny any wrongdoing.

Campaigners believe this is a landmark case and the outcome of the trial in Milan will cause an earthquake that would reverberate through the oil and gas industry.