A former UBS trader accused of losing $2.3 billion in reckless deals told a jury Tuesday that he lost control amid constant pressure from his managers to make profits.

Kweku Adoboli, 32, testified to a London court that managers at the bank were fully aware of what he was doing and pressured him to "push the boundaries" when he worked at the Swiss bank.

"We were told you wouldn't know where the limit of the boundary was until you got a slap on the back of the wrist," he told the Southwark Crown Court. "We found that boundary, we found the edge, we fell off and I got arrested."

The former trader denies two counts of fraud and four counts of false accounting between October 2008 and September 2011.

Adoboli said he felt pressured to take a more bullish approach to trading when a fellow trader mocked his conservative stance in an email that was circulated within the company. He said he did not feel he had full control of the trades under the pressure.

"I absolutely lost control. I was no longer in control of the decisions around the trades we were doing," he said.

Adoboli was a senior trader in exchange traded funds, which are listed and tradeable on stock exchanges and usually track a market index. At one point he risked losing the bank $12 billion, prosecutors say.

The incident was a major blow to UBS, one of the European banks hardest hit by losses from the U.S. subprime mortgage market. Separately, the bank announced Tuesday it planned to layoff as many as 10,000 jobs worldwide as a cost-cutting measure.

Adoboli took the stand for the first time last week.