Singer Morrissey has alleged he was sexually assaulted by a Transportation Safety Administration officer at San Francisco International Airport. The agency has denied the allegations.

The former Smiths frontman said he was leaving the airport on 27 July on his way to London when he was stopped by an airport security screener and groped. The 56-year-old singer wrote a letter posted on the fan website True to You about the incident, the Los Angeles Times reported.

"I went through the usual airport security procedure including the standup 'scanner', and all was well—no bleeps and nothing unusual," Morrissey wrote.

He continued: "Before I could gather my belongings from the usual array of trays I was approached by an 'airport security officer' who stopped me, crouched before me and groped my penis and testicles. He quickly moved away as an older 'airport security officer' approached."

The singer said the incident was caught by airport security cameras. Morrissey also said he was with two British Airways Special Services workers, who counselled him to lodge a complaint against the TSA officer.

"In the interest of imperishable bureaucracy my submitted complain against this 'officer' will obviously be either unread or ignored because, as we all know, on matters of officialism it is not possible to be pleasantly surprised by anything at all," the singer wrote.

However, TSA spokesman Mike England defended the security screener's actions.

"TSA takes all allegations of misconduct seriously and strives to treat every passenger with dignity and respect," England said in a statement provided to the LA Times. "Upon review of closed-circuit TV footage, TSA determined that the supervised officer followed standard operating procedures in the screening of this individual."

According to the Guardian, an official explained the arrival of the second officer to screen the singer was normal procedure.

"During the screening process, if an anomaly is detected, secondary screening is required to ensure the passenger does not have threat items, such as explosives, concealed under clothing," the official said.