Britain's scandal-hit Barclays bank has posted a 68% jump in first-half net profits, as it pushed ahead with a major restructuring that will shrink its investment bank division.

Earnings after taxation surged to £1.13bn in the six months to June, from £671m a year earlier, Barclays said in a results statement.

The group also bounced back into profit in the second quarter with a net figure of £161m, after a loss of £168m last time around.

Barclays, which has been plagued by a series of scandals in recent years, added that it was buoyed by its personal and corporate banking and its credit card unit, amid a major group-wide restructuring.

Adjusted pre-tax profits however sank 7% to £3.349bn in the first half, hit by a 46% slump at its investment banking operations.

Barclays had launched plans in May to shrink its investment bank in a radical restructuring which will axe 19,000 jobs across the group over the next two years.

"We committed to simplify, focus and rebalance the group to deliver higher and more sustainable returns across the cycle, while structurally reducing our cost base and strengthening our capital position," said chief executive Antony Jenkins in the statement.

"We are making encouraging progress in executing this plan. Profits before tax in Personal and Corporate Banking and Barclaycard were up 23% and 24% respectively."

He added: "Performance in the investment bank was impacted by the repositioning underway as well as difficult trading conditions in the quarter, but it is where we expected it to be at this point."

Barclays, which was at the heart of the Libor interest-rate rigging scandal in 2012, also facing investigations along with other major lenders over possible manipulation of foreign exchange trades.

The bank's ongoing attempts to repair its reputation were hit in June after New York prosecutors sued Barclays for fraud, saying it ran a "dark pool" securities trading operation to the benefit of "predatory" high-frequency traders.

Barclays added that it continued to provide information to the relevant regulatory authorities over the matter.