Royal Bank of Scotland has yet to decide whether the £390m fine for rigging Libor should have an impact on any bonuses for Stephen Hester for this year amid renewed focus on the chief executive's pay.

Sir Philip Hampton, the bank's chairman, told the Guardian that a decision about Hester's 2013 bonus will be made "at the end of the year and will take into account all the relevant factors".

Ahead of an appearance before the banking standards commission on Monday, the RBS chairman said : "It is far too early, in February, to speculate on what his bonus for 2013 will be".

Hampton said on Wednesday, when the fine for rigging Libor was announced, that the bank did not intend to claw back the £2m bonus Hester had been awarded for 2010, £780,000 of which is due to be paid next month in shares. Hester will then hold the shares for another year.

The bonus for 2010 is the only one Hester has received since being appointed to run RBS following its £45bn taxpayer bailout, which led to the departure of his predecessor Fred Goodwin. He waived any bonus for 2012 in June when the bank was mired in an IT crisis. A year ago he waived a bonus of nearly £1m for 2011 following political outcry.

When the fine was announced last week, Hampton said the bank was considering whether to ask former directors to voluntarily repay bonuses paid out in the past.

Lord Oakeshott, the Liberal Democrat peer, said last week that Hester should not keep his £2m bonus in the light of the Libor fine.

The business secretary, Vince Cable, declined to comment on the chief executive's bonus but said: "The one area where RBS is underperforming is in British business banking and SME lending. That's where I want Mr Hester to be concentrating his energy."

Hampton and Hester are expected to be questioned on bonuses at Monday's banking standards commission, chaired by conservative MP Andrew Tyrie. The commission last week heard from the bosses of Lloyds Banking Group, Barclays and HSBC, in the wake of the fine for rigging Libor. The investigation exposed electronic exchanges between traders discussing the fixing of Libor. One said: "I'm like a whore's drawers," while another said: "It's just amazing how Libor fixing can make you that much money."

The commission, set up in the fallout from the Barclays Libor fine in June, is also taking evidence on Monday from John Hourican, the head of the RBS investment bank who is to leave shortly. Hourican is waiving a £4m bonus but will receive a £700,000 payoff to ease his departure. Hampton has described the situation as tough on Hourican, who is stepping down "in recognition of the management issues" that arose from the Libor rigging even though he had no personal involvement.

The commission is also taking evidence from Peter Nielsen, chief executive of the markets division within the investment bank, as well as Johnny Cameron, who was running the RBS investment bank at the time it was bailed out by the taxpayer in 2008. Cameron has pledged never to run a bank again in an agreement with the Financial Services Authority, which has agreed not to pursue any regulatory action against him.

RBS is expected to book the £290m Libor fine in the 2012 financial year – when it will reduce bonuses for investment bankers – even though it was announced at the start of the new financial year. The chancellor, George Osborne, has told the bank to find the £300m part of the fine going to US regulators from bankers' pay.

The former chief executive of Lloyds Banking Group, Eric Daniels, will give evidence on Thursday in a session about the mis-selling of payment protection insurance. Daniels was forced to hand back 40% – £580,000 – of his £1.45m bonus from 2010 after the bank began to take provisions for mis-selling the insurance product. Those provisions have now reached £5.2bn after his successor, António Horta-Osório, decided to proceed with paying claims.