PM Ranil Wickremesinghe has called for a detailed report into the firing of teargas to disperse the protestors.
The suspect military officer is said to be a close friend of former defence secretary Gotabhaya Rajapaksa, said the official.
After the present regime took over, many major protests took place, but the police had not allowed any of them to proceed up to the Presidential Secretariat, an official of the Presidential Secretariat said.
A conspiracy trial?
He noted that there was suspicion that this incident, which happened when the president was not in the country, could be a trial for a major conspiracy.
The authorities concerned disregarded a warning by state intelligence that a group stationed near Taj Samudra Hotel was planning to enter the Presidential Secretariat.
President says political hand
Commenting on this incident, president Maithripala Sirisena said yesterday (08) that a political hand was behind this protest by disabled soldiers, despite being promised a pension.
These soldiers did not know that they were being used, he said.
Defence ministry officials had gone there and explained matters to them, to which they had agreed, but one of them had given a call, after which the attempt was made to enter the Presidential Secretariat, said the president.
Those involved had already planned what they should do, he added.