By Mohammed Abbas

TOKYO (Reuters) - British Prime Minister David Cameron began on Tuesday a tour of Japan and Southeast Asia vowing to explore opportunities the region offers to bolster Britain's sluggish economy by boosting trade and investment ties.

Hours before Cameron's plane touched down in Tokyo, Japanese carmaker Nissan Motor Co said it would spend $200 million to build a new hatchback at its British plant.

British officials said, in all, more than 200 million pounds ($317.19 million) of Japanese investment in Britain was due to be announced during Cameron's visit, including a Mitsui Corp wind turbine research project in Edinburgh and a Panasonic fuel cell research centre in Cardiff.

"This trip is really about British business, British exports and investment from Britain into these countries, and investment from these countries into Britain," Cameron told reporters.

"Nissan's investment in the UK is a huge vote of confidence in the skills and flexibility of the UK workforce. We want to attract more investment like this," said Cameron, due to meet Japanese Prime Minister Yoshihiko Noda later on Tuesday.

Nissan's new car will go into production in 2014 and create 225 jobs at its Sunderland factory in northern England and 900 more at the carmaker' s British suppliers.

The new commitment comes on top of $200 million earmarked for production of a new compact car Nissan announced last month and will take manufacturing capacity at Britain's biggest car plant beyond 550,000 vehicles a year.

Accompanied by about 35 executives from defense, energy, construction and other firms, Cameron will head from Tokyo to Indonesia on Wednesday and Malaysia the following day.

On Friday, Cameron is due in Myanmar where he will meet pro-democracy leader Aung San Suu Kyi as the first major Western leader to visit the long-isolated country since a 1962 coup began a half century of military rule.

His visit, confirmed by sources in Myanmar, comes nearly two weeks after Suu Kyi's National League for Democracy won historic by-elections by a landslide, convincing the United States and European Union to consider relaxing economic sanctions imposed years ago in response to human rights abuses.

Cameron's two-year-old coalition government is trying to boost British manufacturing to lessen reliance on financial services roiled by the 2008-2009 global financial crisis. It also seeks to limit the economy's exposure to the crisis-hit euro zone by doing more business with fast-growing Asian economies and emerging markets around the world.

DEFENCE, NUCLEAR ON AGENDA

In Japan, Cameron and Noda are expected to discuss cooperation on defense manufacturing, nuclear decommissioning and free trade, as well as the violence in Syria and relations with Iran and North Korea.

Architecture and infrastructure firms and nuclear industry executives are with Cameron, reflecting British hopes for a slice of the vast sums Japan will spend to clean up and rebuild regions devastated by last year's earthquake and tsunami.

The tsunami washed away swathes of Japan's northeastern coast and wrecked the Fukushima nuclear plant north of Tokyo, releasing radiation and forcing 80,000 people from their homes.

"British companies have significant expertise in nuclear decommissioning and clean-up, with 19 nuclear sites in the UK currently being managed through the process," Cameron said.

He also hopes to capitalize on Japan's recent decision to relax its self-imposed decades-old ban on military equipment exports, which could open the way to the joint development of arms by Japanese and British firms. Progress on securing a free trade agreement between the European Union and Japan is also on the agenda.

In Indonesia, the world's fourth most populous country, the British delegation will focus on deals in energy, construction, retail, pharmaceutical, defense and financial services sectors.

"There's enormous upside potential, and I think a number of businesses are very excited by the fact we're going to Indonesia," Cameron told reporters.

In Malaysia, Britain aims to tap the Southeast Asian country's position as a regional education hub, with many Western universities setting up campuses there.

The British leader also hopes to bolster moderate forces in the two Muslim democracies.

"There's the issue of encouraging moderate Islam and showing that Islam and democracy are compatible. And I think that both Indonesia and Malaysia are great examples of that," Cameron said.

($1 = 0.6305 pounds)

(Additional reporting by Adrian Croft and Aung Hla Tun; Writing by Mohammed Abbas and Tomasz Janowski; Editing by Robert Birsel)