The yuan weakened over 1% in onshore trade on Monday after Chinese markets reopened following an extended Lunar New Year break, pulling down already bruised Asian currencies as worries over the coronavirus outbreak cast a pall over the region.

Trading for the first time since January 23, the onshore yuan shed 1.2% to trade at 7.019 against the dollar, the weakest since Dec. 12, 2019, as the death toll in China from the fast-spreading virus rose to 361 as of Sunday.

In a show of support, China's central bank unexpectedly lowered the interest rates on reverse repurchase agreements and also injected a total of 1.2 trillion yuan ($173.81 billion) into money markets on Monday.

The measures, however, did little to assuage markets. Investors shaved off about $420 billion from the benchmark Shanghai Composite index, while yields on the country's 30-year government bonds fell.

"The coordinated and pre-emptive measures by Beijing will go a long way to soften the blow, but confidence remains fragile amid high uncertainty," Lavanya Venkateswaran, economist at Mizuho Bank's Asia & Oceania Treasury Department said.

Knock-on effects from the yuan's dive and worries over the outbreak hurting demand from China kept most regional units under pressure. The Thai baht weakened 0.1%. The region's best performer across the last two years, the currency has shed over 4% since the year began.

Last week, the Thai Tourism Ministry warned that reduced travel from China alone could result in 50 billion baht ($1.52 billion) of lost tourism revenue. The Malaysian ringgit eased 0.4% while the Taiwan dollar and South Korean won lost about 0.3% each against the dollar.

Even the Indian rupee eased, despite data from a private survey which showed manufacturing activity in the country expanded at its quickest pace in nearly eight years in January. The Indonesian rupiah tumbled nearly 0.6% to trade at 13,725 against the dollar - weakest in nearly three weeks - despite the central bank stepping in to support the currency.

An official said Bank Indonesia was intervening in spot foreign currency trading as well as domestic non-deliverable forward and bond markets to stabilise the currency, whose fall he attributed to the sudden drop in Chinese markets.

So far this year, the currency is the region's best performer and sole gainer, firming 1%, as a series of rate hikes across 2018 to defend against capital outflows continue to lend support.