Deutsche Bank more than doubled its first-quarter net profit to €575m, benefiting from lower legal costs for past misdeeds and a rebound in debt trading.

Germany's flagship lender beat expectations of analysts who had expected the bank to post a first-quarter net profit of €522m. 

"Client engagement is strong, asset flows are returning across the bank and activity is picking up. Our cost-cutting efforts are starting to pay off, while we have reduced complexity significantly," the bank's chief executive John Cryan said. 

The bank's litigation reserves decreased to €3.2 billion in the quarter, after it had booked record fourth-quarter sums for settlements such as over the sale of toxic mortgages and sham Russian trades. 

Provisions for possible future legal action were flat at €2.4 billion. 

Earlier this month, the US Federal Reserve fined Deutsche Bank $157m for violating foreign exchange rules and running afoul of the so-called Volcker Rule on speculative investments.

This leaves a probe into sanctions violations as the only large remaining litigation issue. 

Revenues at Deutsche Bank's cash-cow bond-trading division were up 11% in the quarter as it benefited from a surge in trading across interest rate products, commodities and foreign exchange (FICC), while sales were down 10% in equity trading.

The bank said its total revenues were down 9% at €7.3 billion in the quarter. 

The bank's core tier 1 equity ratio rose to 14.1% from 10.7% a year earlier, strengthened by an $8.5 billion cash call earlier this month.