The Myanmar flag flies during a march in Yangon.
Johnson is scheduled to visit Rakhine later on Sunday.
After months of denying abuses by its troops, Myanmar's military admitted in January that security officers had assisted in killing 10 Rohingya men in Rakhine's Inn Din village.
A Myanmar government spokesperson, Zaw Htay, said that "action according to the law" would be taken against seven soldiers, three members of the police force and six villagers as part of an army investigation that was initiated before the Reuters report was published.
U Zaw Htay said that legal action will be taken based on the results of the Tatmadaw's court martial investigation.
On Friday, Reuters worldwide news agency published a report that provided more details that led to the killing of the 10 people, which the Tatmadaw said were suspected terrorists.
Others have no home to return to after their villages were torched in the military crackdown.
The military's version of events is contradicted by accounts given to Reuters by Rakhine Buddhist and Rohingya Muslim witnesses.
The Reuters investigation of the Inn Din massacre was what prompted the arrest of two of the news agency's reporters.
The 10 victims were allegedly singled out by soldiers from among hundreds of men and women and children who had sought refuge at a nearby beach.
But foreign governments and worldwide aid groups, including the United Nations, have criticised the Myanmar government and the Tatmadaw for alleged atrocities against Muslims in the area, which drove more than 650,000 people to flee to neighbouring Bangladesh.
That public admission followed the arrests of two Myanmar journalists who were investigating the massacre and are now facing up 14 years in prison on charges of possessing secret documents.
Last week, the US-based Associated Press reported more cases of mass killings being uncovered in another village, but the government's Information Ministry denied the report.
During a visit, Johnson said he spoke to de facto leader Aung San Suu Kyi about the situation during a visit to Myanmar this week.
Yesterday Mr Johnson visited a refugee camp at Cox's Bazar in Bangladesh ahead of his talks with Ms Suu Kyi.
Johnson wrote on Twitter that he raised the "importance of [Myanmar] authorities in carrying out full and independent investigation into the violence in Rakhine".
The United Nations has described the exodus of Rohingya as a "textbook example of ethnic cleansing".
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