ISLAMABAD (AFP) - Pakistan's fugitive former oil and gas chief has been arrested in Abu Dhabi on suspicion of embezzling US$850 million (S$1 billion) in a scandal that could spark a criminal case against the prime minister, an official said on Wednesday.

Tauqir Sadiq was arrested a week after Pakistan's top court ordered a case to be registered against Prime Minister Raja Pervez Ashraf over the matter, raising pressure on the government as it nears the end of its five-year term in office.

Sadiq is accused of taking US$850 million in kickbacks and commissions while head of Pakistan's oil and gas regulatory authority between 2009 and 2011, at a time when Mr Ashraf was water and power minister. Sadiq fled Pakistan last year.

"We can confirm his arrest. He has been detained in Abu Dhabi," said Mr Zafar Iqbal, spokesman for Pakistan's anti-corruption National Accountability Bureau (NAB), which has been investigating the graft allegations.

Mr Iqbal told AFP that Sadiq could return to Pakistan "in the next few days" and "as soon as the legal formalities are complete".

The next Supreme Court hearing in the case is due on Thursday.

On Jan 24, the court ordered a case to be registered against Mr Ashraf, Interior Minister Rehman Malik and another senior member of the main ruling Pakistan People's Party over Sadiq's appointment in 2009 and absconding in 2012.

The court has also ordered Mr Ashraf's arrest over another corruption probe dating back to his tenure as water and power minister.

Members of the government accuse judges of waging a politically motivated witch hunt against the administration, which in March 2013 will become the first elected civilian government in Pakistan to complete a full term in office.

In June last year, the Supreme Court sacked Mr Ashraf's predecessor over his refusal to ask Switzerland to reopen corruption cases against President Asif Ali Zardari.