Nigerian authorities seized $8 million in cash stashed in six plastic bags on a bus at the international airport in the commercial capital of Lagos, the customs service said on Wednesday.

The cash, in an unspecified foreign currency, was wrapped in 20 sealed packages inside the bags, was found on the bus at the Murtala Muhammed airport on 16 January, according to a statement from the customs authority.

The bus driver was arrested at the scene, the authority said, but it was not yet clear whose money it was.

Under Nigerian law, anyone seeking to cross a border with more than $10,000-worth of cash must declare it to customs.

Large seizures of cash and goods are not uncommon in Nigeria, which ranked 146 out of 180 countries on Transparency International’s 2019 corruption perception index.

Last year, authorities seized $40 million worth of jewellery and a customised gold iPhone belonging to a former oil minister, while in 2017 the anti-fraud unit said it had seized $43.4 million in cash from a Lagos apartment.

Comptroller-General of Customs, Col Hameed Ali, said extra surveillance had been put in place at the airport to counter money laundering and terrorism finance.