South Korea's Joint Chiefs of Staff (JCS) said the projectiles were fired at 2.59 a.m. and 3.23 a.m. from Yonghung, South Hamgyong Province, into the East Sea, reports Yonhap News Agency.
Both projectiles flew around 220 km at an altitude of about 25 km, according to the JCS, adding that they flew at a top speed of Mach 6.9.
What the North fired appears to be a new type of short-range ballistic missiles, but more analysis was needed, the presidential office Cheong Wa Dae said, adding that it has convened an emergency meeting of security-related ministers to discuss the development.
Earlier in the day, American media also reported, citing US officials, that North Korea fired two short-range ballistic missiles Friday.
"We are monitoring the situation in case of additional launches and maintaining a readiness posture," the JCS said.
In Washington, a senior US official said he is aware of the North's latest launches.
"We are aware of public reports of additional missile launches from North Korea today," the official told Yonhap News Agency.
"We continue to monitor the situation and are consulting closely with our South Korean and Japanese allies."
Shortly after the firings, US Secretary of State Mike Pompeo said that Washington was continuing North Korea dialog.
He made the remarks while was speaking on the sidelines of the 52nd Association of Southeast Asian Nations Foreign Ministers' Meeting in the Thai capital of Bangkok, adding that "you should never doubt what we may be communicating to the North Koreans. There are conversations going on even as we speak".
Over the past eight days, Pyongyang has launched three rounds of weapons tests, thought to be short-range ballistic missiles and rockets, with the latest on early Friday morning.
Last week, North Korean leader Kim Jong-un also unveiled a new submarine thought to be capable of launching missiles.
Meanwhile at the White House, US President Donald Trump insisted he had no problem with the launches because there had been no agreement with North Korea on short-range missiles.
Trump and Kim had agreed during their inter-Korean border meeting on June 30 to resume working-level talks on denuclearizing the regime.
"We never discussed that (missile launches). We discussed nuclear. What we talked about is nuclear," he told reporters on Thursday.
( With inputs from IANS )