The international medical charity Doctors Without Borders says at least 6,700 members of the persecuted Rohingya Musliminfo-icon minority group were killed in state-sponsored violence in Myanmarinfo-icon only in a period of one month beginning on August 25.

The announcement was made by Doctors Without Borders, also known by its French acronym MSF, on Thursday.

"At least 6,700 Rohingya, in the most conservative estimations, are estimated to have been killed, including at least 730 children below the age of five years," the aid group said.

The MSF said the figures had come from six surveys of more than 2,434 households in Rohingya refugee camps and covered a period of one month.

"We met and spoke with survivors of violence in Myanmar, who are now sheltering in overcrowded and unsanitary camps in Bangladeshinfo-icon," said the group's medical director, Sidney Wong.

"What we uncovered was staggering, both in terms of the numbers of people who reported a family member died as a result of violence, and the horrific ways in which they said they were killed or severely injured," he added.

The MSF said that gunshot wounds had been the cause of death in 69 percent of the cases after Myanmar's armyinfo-icon launched "clearance operations" in Rakhine.

Another nine percent were reported burned alive inside houses, while five percent died from fatal beatings, according to the MSF survey.

The revelation was made as Myanmar's army has so far denied widespread accounts of violence against the Muslim Rohingya minority and has said that only 400 people died in the first few weeks of a new wave of "security operations" that began on August 25.

Separately on Thursday, Myanmar's government announced that it had arrested two journalists over accusations of possessing "important secret papers" related to the widespread violence in the country's western Rakhine State, where the Rohingya are being persecuted.

The Ministry of Information in Myanmar said in a statement that the two journalists, identified as Wa Lone and Kyaw Soe Oo, worked for the Reuters news agency and had been detained at a police station on the outskirts of Yangon, the Southeast Asian country's largest city.

The reporters "illegally acquired information with the intention to share it with foreign mediainfo-icon," said the statement, which was accompanied by a photo of the pair in handcuffs.

The ministry said the journalists obtained the information from two policemen who had worked in Rakhine State, adding that the four would face charges under a section of Myanmar's colonial-era Official Secrets Act, which carries a maximum prison sentence of 14 years.

The Reuters news agency said the pair went missing on Tuesday evening after they had been invited to meet the police officials over dinner.

"Reuters reporters Wa Lone and Kyaw Soe Oo have been reporting on events of global importance in Myanmar, and we learned today that they have been arrested in connection with their work," Stephen J. Adler, the president and editor-in-chief of Reuters, said in a statement.

"We are outraged by this blatant attack on press freedom. We call for authorities to release them immediately," he added.

Myanmar has barred foreign groups and reporters from entering Rakhine, which has been under military siege since late last year and where horrific violence is being reported against the minority Rohingya Muslims.

More than 600,000 Rohingya Muslims have sought sanctuary in Bangladesh after the military in the mostly-Buddhist Myanmar intensified the crackdown in villages across the northern parts of Rakhine State on August 25, using a number of armed attacks on security checkpoints as a pretext.

Myanmar's officials use the term "Bengali" to refer to the Rohingya. The group, which has lived in Myanmar for decades, has been denied citizenship in both Myanmar and neighboring Bangladesh.

During the past three months, government troops, apart from raping, have been committing killings, making arbitrary arrests, and carrying out mass arson of houses in hundreds of predominantly-Rohingya villages in the restive state.

The United Nationsinfo-icon has already described the Rohingya as the most persecuted community in the worldinfo-icon, calling the situation in Rakhine similar to "a textbook example of ethnic cleansing."