Santander, the Spanish bank, yesterday said it had suspended a derivatives analyst charged by the US Securities and Exchange Commission with insider trading related to the $39bn BHP Billiton bid for PotashCorp.

Juan José Fernández García, the analyst, was charged together with Luis Martín Caro Sánchez after the SEC accused them of making nearly $1.1m in illegal profits by buying "out of the money" call options in PotashCorp, the fertiliser producer, and then selling them after the bid by BHP Billiton, the mining company, was announced on August 17.

"The bank has acted at all times following the appropriate procedures," Santander said, adding that it would co-operate with investigators and was awaiting results of its own probe as well as the SEC's. "Provisionally, while the investigation is completed, the employee concerned has been suspended from his job."

On his details with LinkedIn, an online business networking service, Mr Fernández García calls himself head of European equity derivatives research at Banco Santander, but an employee of Santander described him as an analyst and said he was not in charge of Europe.

No details had emerged by last night about Mr Caro Sánchez, although both men were described by the SEC as residents of Madrid. Neither could be reached for comment.

Santander was among a group of banks that helped BHP pull together a $45bn loan facility for the PotashCorp bid.

The bank declined to comment on how any inside information might have been leaked to one of its employees.

"That's exactly what our internalinvestigation is trying to find out," said one person familiar with the discussions over the allegations. Mr Fernández García was on holiday when the SEC charges were announced on Tuesday and had been informed by Santander of his suspension, the person said.

The SEC has moved fast in the case, the first brought by a new specialised market abuse unit in its enforcement division.

A court order to freeze the duo's assets was obtained on Friday, only three days after the BHP bid was announced. The regulator is understood to believe that speed was of the essence, given the men charged are both Spanish residents and had been seeking to move their allegedly illegal profits out of the US.