HANOI, Jan 23 (Reuters) - A German business delegation, including top firms for tunnel machines, wind farms and industrial supplies, is joining President Frank-Walter Steinmeier in a visit to Vietnam starting on Tuesday, as Berlin pushes its China de-risking strategy.

German companies have invested over $3 billion in the Southeast Asian manufacturing hub, with automotive giant Bosch being the main investor, according to the German chamber of commerce in Vietnam, which sees the country as an important partner to diversify some activities from China.

During the visit, Steinmeier and German labour minister Hubertus Heil are expected to sign with their Vietnamese counterparts a memorandum of understanding on skilled labour mobility to facilitate transfers of Vietnamese workers to Germany.

Among companies participating in the business mission is Herrenknecht, which dominates the global market for tunnel boring machines. It is already selling tools for the building of the metro in Ho Chi Minh City, amid Vietnam's plans to expand its railway and metro systems.

Wind farm developer PNE AG is also part of the delegation, possibly trying to tap into Vietnam's planned expansion in the offshore wind sector, despite regulatory delays.

Building materials multinational Knauf Gips KG and automotive sector's supplier Tesa are among other participants. Both already have operations in Vietnam.

The visit "underlines Germany's interest in looking beyond China and diversifying its economic relations," said Florian Feyerabend, the representative in Vietnam for Germany's Konrad Adenauer Foundation, a think tank.

He also said the expected labour agreement was part of Germany's strategy to recruit skilled workers from abroad, noting that in the 1980s thousands of Vietnamese workers moved to East Germany.

Steinmeier's visit was delayed by a year because of a political reshuffle in Vietnam that led early last year to the resignation of the country's former president.

In a sign of Berlin's growing interest in Vietnam, Steinmeier's visit follows a trip to Hanoi by German Chancellor Olaf Scholz in November 2022, the first then for a German leader in more than decade.

After meetings with leaders in Hanoi, Steinmeier will visit Ho Chi Minh City, the country's business hub, on Wednesday. (Reporting by Francesco Guarascio and Phuong Nguyen; Editing by Kim Coghill)