MOSCOW, March 9 (Reuters) - Russia was storming the town

of Sudzha on Sunday after special forces used a gas pipeline to

surprise Ukrainian units as part of a major offensive to eject

Ukrainian soldiers from the western Russian region of Kursk,

pro-Russian war bloggers said.

Thousands of Ukrainian soldiers seized about 1,300 square km

of Russia's Kursk region in August last year in what Kyiv said

was an attempt to gain a bargaining chip in future negotiations

and to force Russia to shift military forces from eastern

Ukraine.

Yuri Podolyaka, a Ukrainian-born, pro-Russian military

blogger, said Russian special forces had walked about 15 km

along the inside of a major gas pipeline and some had spent

several days in the pipe before surprising Ukrainian forces from

the rear near Sudzha.

Sudzha is the home of major gas transfer and measuring

stations on a pipeline that used to carry Russian natural gas

into the Ukrainian gas transmission system for onward

transportation to Europe.

Pro-Russian war blogger Two Majors said a major battle was

under way for Sudzha and that Russian forces had surprised

Ukrainian soldiers by entering the town via a major gas

pipeline.

Russian Telegram channels showed pictures of special forces

in gas masks and lights, some using colourful Russian curses,

along the inside of what looked like a large pipe.

Reuters was unable to verify the reports immediately.

"Fighting continued throughout the night in Sudzha," said

Podolyaka. "The fighting did not stop."

Another war blogger, Yuri Kotenok, said that Ukrainian

forces have been moving equipment away from Sudzha, closer to

the border.

"At the moment, our units are attacking in the north-eastern

part of Sudzha and fighting in the area of ​​Lomonosov Street

and the industrial zone of Sudzha," Kotenok said.

Ukraine's incursion into Kursk last August was the most

serious attack on Russian territory since the Nazi invasion of

the Soviet Union in 1941.

In recent weeks and months, Russian forces have pushed

Ukrainian forces back across the Kursk front, placing tens of

thousands of Ukrainian troops in danger of being encircled.