The arrested suspect, who is said to have taken Shahzad to Pakistan's tribal belt to attend bomb-making training and provided him with money, is believed to have links with Tehreek-e-Taliban Pakistan (TTP).
According to the report, Pakistan has granted access to the arrested Pakistani suspect to the US investigators.
The investigators are working on matching the information given by him with that provided by Shahzad.
They are also looking into the phone records, e-mails and other communication exchanged between two men to determine their links with Pakistani Taliban, the report said.
However, the US authorities have declined to disclose the name of the arrested suspect.
The information provided by the arrested Pakistani suspect on the attempted Times Square bombing matches with that of Shazad, barring few inconsistencies in the chronologies among others, officials were quoted as saying in the report.
Experts said that US would be forced to intensify pressure on Pakistan to launch another offensive in its restive tribal area, if the arrest of the Pakistani suspect ascertains TTP involvement behind the attack.
United States has earlier indicated the involvement of TTP behind the Times Square bombing.
Meanwhile, a senior US administration official said that they are yet to find concrete evidence to link Shahzad with TTP