Train services on the busy Yamanote Line in downtown Tokyo resumed Friday morning after operations were suspended for checks following problems with some pantographs detected the previous night, JR East said.

Both the inner and outer loops of the JR Yamanote Line, which encircles central Tokyo, were suspended from the first scheduled services, causing widespread disruption to commuters. A total of 141 trains on the line and the Keihin-Tohoku Line running alongside it were canceled on Friday, affecting around 197,000 people, the operator said.

After the resumption, the Yamanote Line operated with considerably reduced services, JR East said.

Services on the Keihin-Tohoku Line, which were suspended on a section running near the loop line, had fully resumed.

Trains on the Yamanote Line's outer loop were canceled Thursday night due to problems with the pantographs, the apparatus that connects carriages to overhead power lines.

Services on the Yamanote Line were suspended after an abnormality was detected at a power line-related facility near Shimbashi Station, the operator said.

Meanwhile, the Keiyo Line was also temporarily suspended from the scheduled start of services on Friday after smoke was seen on the tracks at Hatchobori Station in Tokyo late Thursday. While operations partially recommenced, services were delayed.