Kabul, Afghanistan (CNN) -- A suspected Taliban spy who worked at the Afghan Defense Ministry headquarters in Kabul has been arrested after allegedly leaking critical security information to insurgents, officials said Sunday.
Gul Mohammad was arrested last week following a month-long investigation that allegedly uncovered his plans to organize suicide attacks on key Afghan and international installations, according to National Directorate of Security spokesman Litfullah Mashal.
Among the locations to be targeted were the International Security Assistance Force headquarters and an NDS building as well as an Afghan military outpost and police station in Kabul.
Authorities tapped Mohammad's phone and have recordings of the suspect accepting Taliban bribes, Mashal said.
CNN cannot independently verify that account.
Mohammad -- a senior official whose responsibilities at the Defense Ministry included security at a series of checkpoints throughout the city -- was detained Tuesday in Kabul.
Officials said he was in the process of bringing militants to the capital.
Mashal says the suspect had also warned Taliban commanders of impending raids, pointing to recent Afghan security operations in the country's eastern Nooristan province.
His arrest came as officials struggle to put an end to a series of high-profile July attacks.
On Sunday, a suicide bomber's car exploded outside a police headquarters in southern Afghanistan, killing at least 12 police officers, according to an Interior Ministry statement.
Another 14 people -- most of them officers -- were injured in the attack, the statement said.
"The suicide bomber was trying to target police chief headquarters in Helmand" province, but his car full of explosives detonated close to the entrance, said Dawood Ahmadi, a spokesman for the Helmand governor.
The explosion occurred in the provincial capital of Lashkar Gah, widely considered the most dangerous of seven areas handed over to Afghan security forces in recent weeks.
Elsewhere in Helmand, a joint Afghan and NATO raid left two insurgents dead and led to the arrest of two others during a security sweep in the region's Kajaki district.
CNN's Fazel Reshad and Matiullah Mati contributed to this report