By Supantha Mukherjee

STOCKHOLM, Nov 28 (Reuters) - One of two Baltic subsea

cables that were damaged earlier this month in a suspected

sabotage is back online, a spokesman for operator company

Arelion said.

The cable connecting Sweden and Lithuania was repaired as of

Thursday and traffic had resumed at full capacity, spokesman

Martin Sjogren said.

Two subsea cables -- the other linking Finland and Germany

-- were damaged in less than 24 hours on Nov. 17-18, prompting

German Defence Minister Boris Pistorius to say he assumed it was

sabotage.

Undersea cables transmit nearly all the world's internet

data traffic, and are considered critical infrastructure as they

connect the communication backbone between countries.

Investigators have zeroed in on Chinese bulk carrier Yi Peng

3, and Swedish Prime Minister Ulf Kristersson said the country

sent a formal request to China seeking cooperation to help

clarify what happened when the undersea cables were damaged in

the Baltic Sea.

"We are cooperating with Swedish police in their

investigation of our damaged cable," Sjogren said.

"It's very difficult to secure the entire subsea

infrastructure but the international cooperation between

authorities, military and companies is working very well," he

said.

Arelion, once part of telecom company Telia, owns

75,000 kilometers (46,603 miles)of fiber network.

Finland's Cinia, which owns the other cable, has also

started repair work and estimated completion by the end of this

month.