Investigators will focus on the currency notes handed over by the News Of The World (NOTW) to Mazhar Majeed as they look for evidence of spot fixing in the Lord's Test involving Pakistani cricketers. Majeed was arrested by Scotland Yard on Saturday night and the investigators will try and determine if the currency notes bear resemblance to those found in the hotel rooms of several Pakistani players.

The NOTW claimed Majeed was paid £150,000 to arrange a fix involving Pakistan's new-ball bowlers, Mohammad Amir and Mohammad Asif, whom he allegedly asked to bowl no-balls at specific moments of the match. It also alleged that Salman Butt and Kamran Akmal, the captain and vice-captain respectively, were the kingpins in the deal, which involved a total of seven players.

Butt sidestepped the issue at the post-match press conference on Sunday, saying investigations were on. However, a source familiar with such investigations said he would be hard pressed to explain the currency notes allegedly found in his hotel room if they matched those given to Majeed by NOTW.

"If the notes are the same it would be something serious. It would be direct evidence linking him to what has been claimed by [Majeed]," the source said.

The most serious aspect of the issue, the source said, was Butt's alleged involvement, and Majeed's claim that he knew Butt's bowling plan. "The fact that specific overs are to be bowled by specific bowlers and that they get to bowl those overs…then the specific ball as suggested is the kind of ball they offered are issues that raise considerable concern ," the source said.

What will follow now, the source said, is intensive interrogation by Scotland Yard. "I don't think they will make an arrest unless they have some very credible evidence linking the player(s) to this," he said.

The United Kingdom has a specific law under the Gambling Act that criminalises any offence involving cheating in sport and brings such cases immediately under police jurisdiction.

Butt was handed the Test captaincy in a crisis situation in July after Shahid Afridi's sudden retirement from the five-day game following the Lord's Test against Australia. Butt immediately led Pakistan to a thrilling victory over Australia at Headingley, their first in 15 years. A week ago at The Oval, he was once again victorious when Pakistan beat England in another close finish. The weekend's developments, however, have cast a cloud over those achievements.