Repair of the damaged subsea telecom cable linking Finland with Continental Europe via Germany began on the Baltic Sea on Monday.
The so-called C-Lion1 cable was broken last Monday, with some suspecting Russia was somehow involved. However, the Kremlin has denied any involvement in the incident.
The repair ship Cable Vigilance started making its way from Calais, France towards the site last Thursday.
The cable was broken in Sweden's exclusive economic zone, east of the southern end of Öland island, about 700km from Helsinki according to Cinia, the Finnish majority state-owned company that manages the cable.
The firm has estimated that the repair work could be complete by the end of November.
Finnish police said on Monday that the Border Guard's patrol vessel Turva had collected evidence from the site where the cable was broken. The ship headed to the site last week, following a request from Finland's National Bureau of Investigation for assistance.
Cinia has shared photos from the repair ship that show a remote-controlled tracked submarine vehicle being used in the effort.
The day before C-Lion1 was cut, a communications cable between Sweden and Lithuania was also broken. Swedish authorities are investigating the incident.
Last week it was reported that a Chinese vessel, the Yi Peng 3, was observed in the area around the time both cables were broken. Its beacon signal was turned off from Sunday evening until early Monday.
According to reports from public broadcasters SVT in Sweden and DR in Denmark, "several countries" have been holding diplomatic negotiations with China about the matter. The broadcasters said the aim of the talks is to get approval from the Asian country to examine the Chinese ship.
The Yi Peng 3 has remained anchored at sea between Denmark and Sweden for days, with naval and coast guard ships belonging to Denmark, Sweden and Germany nearby.
There is no conclusive evidence so far that the Chinese ship was involved in damaging the cables, however.
Finland's National Bureau of Investigation has opened a criminal investigation into the incident, approaching it as a case of suspected aggravated property damage and aggravated telecommunications interference.
Last week, a Chinese foreign ministry representative, Lin Jian, told news agency Reuters that China was prepared to hold discussions about submarine infrastructure security. However, he said that he was not aware of details regarding Yi Peng 3.
Spanning from Helsinki to Rostock, Germany, C-Lion1 is around 1,173 km long. It was put into use in 2016, linking Central European communication networks with Finland and other Nordic countries, according to Cinia.
