TOKYO, March 28 (Reuters) - Japanese government bond (JGB) yields fell on Friday as investors bought safe-haven assets amid worries about the outlook of the economy following U.S. President Donald Trump's trade tariff announcement.

The 10-year JGB yield fell 2.5 basis points to 1.56% and the two-year JGB yield fell 1 bp to 0.87%. The five-year yield fell 1.5 bps to 1.165%.

Trump on Wednesday unveiled his plan to implement a 25% tariff on imported cars and light trucks effective April 3, while the duty on auto parts begins on May 3.

Investors are also bracing for a wave of reciprocal tariffs Trump plans to unveil next week, although the president has hinted there may be room for flexibility.

"Investors turned to a risk-off mode and bought JGBs as they were worried about the economy weakening," said Miki Den, senior Japan rate strategist at SMBC Nikko Securities.

"Also a sell-off of local equities prompted investors to buy the bonds," he said.

Japan's Nikkei average fell to a two-week low on Friday in a broad sell-off, with automakers leading the declines over the potential impact of U.S. tariff plans.

Strong outcome of the Bank of Japan's regular bond buying earlier in the session also lifted sentiment, said Den. The BOJ bought bonds with maturities ranging from three to 25 years.

The 20-year JGB yield fell 2 bps to 2.27% and the 30-year JGB yield fell 3.5 bps to 2.545%.

The 40-year JGB yield slipped 6.5 bps to 2.805% to its lowest level since March 6.

(Reporting by Junko Fujita; Editing by Mrigank Dhaniwala)