Asia Pacific markets started the trading week with gains despite China reporting that its economy grew at the lowest official pace in 28 years.

The world's second-largest economy grew 6.6 percent in 2018, which matched analysts' expectations, and was lower than a revised 6.8 percent growth in 2017. Fourth quarter GDP growth was 6.4 percent, which was also in line with expectations.

"I think what we're seeing actually in the fourth quarter is that while the economy is decelerating, we actually still have some of the supports," Helen Zhu, head of China equities at BlackRock, told CNBC's "Street Signs" on Monday. "For example, for most of the quarter, from the export front loading impact that we had probably before the Argentina G-20 (summit) when people's expectations regarding trade became a little bit more optimistic."

Chinese President Xi Jinping and U.S. President Donald Trump agreed to a 90-day pause in tariff escalation at the G-20 summit in Argentina late in 2018.

While Beijing's official GDP figures are seen as one of the crucial indicators of China's economic health, many outside experts have expressed skepticism about the veracity of the numbers.

Raymond Yeung, chief economist for Greater China at the Australia and New Zealand Banking Group, wrote in a note that China's GDP numbers are "not an accurate gauge" of its economic growth. Still, he pointed out, the gap between the actual figures and the official targets usually shapes the government's policy stance.

"Falling producer prices and new export orders point to a slowdown in China's growth momentum," Yeung added. "To celebrate the 70th anniversary of the founding of the People's Republic of China in 2019, President Xi (Jinping) will still likely launch growth-supportive policies."

The mainland Chinese markets, closely watched as a result of the ongoing U.S.-China trade fight, saw gains on the back of the data release. The Shanghai composite rose more than 0.5 percent to close at about 2,610.51 while the Shenzhen composite gained 0.607 percent to end its trading day at around 1,330.17. The Shenzhen component also advanced 0.592 percent to close at approximately 7,626.24.

Hong Kong's Hang Seng index saw gains of 0.39 percent to close at 27,196.54.