The Libor scandal has become one of the biggest to engulf the banking industry in recent years and has claimed the scalps of a raft of senior figures.

Here are the main facts of the investigations into Barclays and Swiss bank UBS, which have already settled with UK and US authorities over their involvement in Libor rigging.

Barclays

British blue chip banking giant Barclays was fined £290m sterling by US and UK authorities in June for attempting to manipulate Libor. It was the first bank to settle with regulators and is widely thought to have suffered the most as it was hung out to dry for its misdeeds, despite many other institutions also being under investigation.

The group was engulfed by a firestorm of controversy after the scandal broke, causing its chairman Marcus Agius and chief executive Bob Diamond to quit. There was public outcry at the underhand tactics used by traders and Barclays staff to influence the rate at which banks lend to each other.

A series of jaw-dropping emails were uncovered by the Financial Services Authority (FSA), including promises of Bollinger, coffees and back-slapping among staff.

In one exchange, a trader is affectionately dubbed "big boy" for helping lower Libor, while another revealed an external trader thanking his Barclays counterpart and adding: "Dude. I owe you big time! Come over one day after work and I'm opening a bottle of Bollinger."

Under new chief executive Antony Jenkins, the bank is seeking a complete overhaul of its culture and practices, telling its staff in a new year memo they must adhere to a new code of conduct or quit.

It has also hired former FSA chief executive Sir Hector Sants to the newly-created role of head of compliance, and it is believed the ex-watchdog has also been tasked with helping rewrite the bank's pay strategy.

UBS

The fine imposed on Barclays was dwarfed by the £940m penalty Swiss bank UBS agreed to pay in December to regulators in the UK, US and Switzerland for Libor-fixing in an even more shocking probe. The FSA said attempts at UBS to manipulate Libor were "extensive and widespread", while it found traders were openly bribing and colluding with external brokers.

At least 45 individuals, including traders, managers and senior managers, were involved in, or aware of, the practice. The regulator recorded at least 2,000 requests for inappropriate submissions and said many more would have been made verbally.

Misconduct at UBS was all the more serious as it had attempted to manipulate Libor submissions at other banks, making corrupt payments to reward brokers for their efforts.

The bank set up unnecessary trades, known as "wash trades", to bribe brokers for their help, which saw one broker firm make £170,000 in illicit fees. UBS also made corrupt payments of £15,000 a quarter to another broker firm over at least 18 months, according to the FSA.

Incriminating conversations between UBS traders and brokers were revealed, saying they would "play the rules" and "return the favour". Bankers referred to each other in congratulatory terms, such as "the three muscateers" (sic), "Superman", and "Captain caos" (sic).

UBS has confirmed that 18 of the staff linked to the scandal have been fired and that regulators have been made aware that the traders are not suitable to work in banking.