Barclays is putting the finishing touches on a plan to boost its capital levels that will likely involve the bank issuing billions of pounds worth of new securities, according to people familiar with the matter.

When it announces its second-quarter results on Tuesday, Barclays is likely to unveil plans to sell convertible bonds and, potentially, new common stock, both of which would boost the bank's cushions to absorb future losses, these people said. The goal is to fill a £7 billion capital deficit that UK regulators recently identified at the bank and to erase investor worries about the adequacy of Barclays' capital.