Almost 700,000 Rohingya have fled the area since last August, carrying stories of atrocities at the hands of troops and vigilante groups in the Buddhist-majority country.
The killings of 10 Rohingya men occurred in the village of Inn Din in September a year ago and the bodies were buried in a mass grave after they were hacked to death or shot and killed by Buddhist neighbours and Myanmar soldiers. "The investigation was being conducted even before Reuters news", Zaw Htay said, adding that he was unable to specify what action would be taken against the 16 people. It is looking at the problems in Rakhine state.
Mr Johnson is due to tour Rakhine State with representatives from the Burmese military later. Two police officers were also arrested, on the same charge of violating a colonial-era law.
A month after the journalists' arrest, Myanmar's army issued a rare statement admitting that security forces took part in extrajudicial killings of 10 Rohingya "terrorists" in Inn Din village.
Judges have denied bail to the two reporters during a pre-trial hearing period, despite calls for their release from human rights groups and diplomats around the globe. Their next hearing is scheduled for February 14.
Myanmar's leader and Nobel Peace Prize Aung San Suu Kyi is facing worldwide criticism, including from fellow peace prize victor Desmond Tutu, for not doing more to stop what the United Nations says are mass killings, rapes and the burning of villages taking place in Rakhine state.
Visiting a border refugee camp, the Foreign Secretary said such a return would only be possible if a "political solution" could be found to remove the great danger from going back.
"Talking just to some of my fellow foreign ministers from around the world, there is so much confusion still, and I think the role of journalism in setting the record straight is absolutely vital", Johnson said.
More than 600,000 men, women and children are estimated to have fled to neighbouring Bangladesh following persecution from the Burmese military in their native state of Rakhine, which began in August.
Members of Myanmar's security forces will face legal action over the hacking and shooting deaths of Rohingya Muslims in restive Rakhine state, a government spokesman said.