TSB chief to lose bonus linked to botched IT upgrade

(Adds amount of bonus, comments from chairman, CEO and politicians)

By Emma Rumney and Lawrence White

LONDON, May 2 (Reuters) - The chief executive of British bank TSB, Paul Pester, will not get a bonus linked to the bank's botched computer system migration, TSB's Chairman Richard Meddings told lawmakers on Wednesday.

Pester and Meddings apologised to members of Britain's Treasury Committee on Wednesday for the migration over the weekend of April 21-22 that left up to 1.9 million customers unable to access their accounts.

Customers were still complaining on Wednesday, more than a week later, as one of Britain's worst-ever bank computer system outages continued.

Pester said that 95 percent of attempted logins to the bank's mobile and digital platforms were now successful, but apologised when members the Treasury Committee confronted him with new complaints from customers about continued problems.

Meddings said that neither he nor Pester would leave the bank over the crisis.

Both men were criticised repeatedly by the politicians on the committee for their attitude during the hearing, in which they insisted that the "underlying engine" of the bank was working well.

"What we are hearing this afternoon is the most staggering example of a chief executive that seems unwilling to realise the scale of the problem," Conservative member of parliament and chair of the committee Nicky Morgan said.

Pester was awarded a bonus worth 1.6 million pounds ($2.18 million) in 2016 linked to the successful completion of the migration, out of a total pay package of 3.7 million pounds, according to the bank's annual report.

It was not immediately clear what the value of the 2017 bonus he was due to receive was, or whether he would forego past awards linked to the migration project.

The bank has appointed consulting firm Deloitte to work out a compensation scheme for affected customers, Meddings said. It has also appointed law firm Slaughter and May to investigate what went wrong.

"I have given a cast iron guarantee no customers will be left out of pocket," Pester said.

The committee members questioned Pester as to how robust testing of the bank's systems had been prior to the migration. Reuters reported earlier on Wednesday that rushed testing had contributed to its subsequent failure.

Pester said the bank had conducted many tests, but still did not know exactly what had caused the outage.

Meddings and Pester said they could not be certain when the ongoing problems with the bank's systems would be fully resolved.

($1 = 0.7351 pounds) (Reporting By Emma Rumney and Lawrence White, editing by Silvia Aloisi and Jane Merriman)