When contacted via Blackberry Messenger, Hilman said he was greeted by some 10 immigration officers as soon as he touched down at the airport.
"The immigration department handed me a refusal of entry notice signed by Sabah immigration deputy assistant director Fenny Fiona J Jeplin.
"The notice was issued after receiving an order from the Sabah chief minister under Section 56(1)(A) of the Immigration Act 1959/63," he said.
Hilman was however detained at 3.30pm and was the only person deported back to Kuala Lumpur while the rest, including Azmin, were allowed entry into the state.
Hilman said he was unclear why he was barred, pointing out that he had previously entered Sabah without trouble.
"The last time I went to Sabah was two months ago, and I have been there three to four times and I've never faced any problems.
"But yesterday, all of them (state immigration officers) were already on stand-by, waiting for me to arrive," he said.
The group was in Sabah to participate in Pakatan Rakyat's Malaysia Day celebrations in Labuan today and Kota Kinabalu tomorrow.