Customers with accounts in Scottish banks are running the risk that their money may no longer be in pounds after independence, a senior UK banker admitted yesterday.

George Culmer, the chief financial officer of Lloyds Banking Group, said he could not give any guarantees about what would happen to money held in Scottish institutions after the independence vote in September.

The referendum dominated Lloyds' annual general meeting in Edinburgh. One trade union shareholder demanded to know whether existing operations and jobs in Scotland would be safe. Others wanted to know what would happen to the Lloyds share price – given that the group includes Bank of Scotland and Scottish Widows.

Download the new Independent Premium app Sharing the full story, not just the headlines

Overarching everything, however, was the prospect of Scotland using a different currency. One shareholder asked: "Can I have your assurance that, if there is a dissolution of the currency union, it will be possible to hold a sterling account in Scotland?"

Mr Culmer admitted he could not give any such guarantee: "I can't give you any assurances with regards as to what the future will hold. It's subject to the vote and subject to how the practical implications and ramifications of that are worked out."

Lord Blackwell, who replaced Sir Win Bischoff as Lloyds' chairman this year, admitted that the prospect of Scottish independence was causing huge uncertainty.

He said that officials were looking into the implications of a "yes" vote but that the bank could not put any money aside to prepare for the costs of independence, because no one knew what these would be. He also conceded he could not guarantee the continuation of the thousands of jobs in Scotland nor the bank's operations north of the border.

Demonstrators outside the meeting protested against Lloyds' decision to freeze pensionable pay for all staff – at the same time as the chief executive, Antonio Horta-Osorio, received a £7.8m pay package.

Alexander Hopkinson-Woolley, a shareholder from the Isle of Wight, said: "This is a massive mistake. Talent in banking is proved by profit. If there is precious little profit, there is precious little talent. This is the emperor's new clothes, justified by financial experts."

Lord Blackwell, however, said the executive bonuses would largely be paid in shares, and although Lloyds was looking for greater flexibility in the size of bonuses paid, this was to ensure executives remained accountable for the group's performance. The executive pay plan and decision to pay staff bonuses worth up to two times their fixed pay was backed by 98 per cent of shareholders at the meeting.

Mr Horta-Osorio also defended the cap on pensionable pay, saying the decision had "not been made lightly". Although he conceded that staff morale at Lloyds had been low in the recent past, he insisted the general mood was now good. He said: "The morale at the bank did dip in the first year of the strategic review but has risen by a third in the last year."