China's invitation to Prime Minister Najib Abdul Razak was also extended to his family, said Rizal Mansor, the aide to the premier's wife Rosmah Mansor.

"The Chinese government invited the PM and his family for this official trip.

"Those familiar with Chinese culture would know that this is a standard custom of China's top leaders who emphasise on strong personal and family relationships with their close counterparts.

"This custom of family relationships is given even greater significance due to the ancient Chinese proverb of '飲水思源' - literally 'when you drink water, think of its source'," said Rizal in a post on Facebook.

Rizal was responding to criticisms against Riza Aziz, Najib's stepson, for travelling together with the first family on an official government trip to China.

Riza is not a government official. He is the co-founder of Red Granite Pictures a US company which produced the hit film 'Wolf of Wall Street'.

Nurashman Najib's Instagram account, showed that his last post was made at the China World Hotel, Beijing.

Rizal said Najib seldom brings his family along on official trips and that the public should focus on the economic benefits that will be derived from the trip.

"There are dozens of trade and investment agreements to be signed during this official trip led by PM Najib which will lead to tens of billions of ringgit in investment, trade and benefits for Malaysia.

"So, why begrudge him on a simple matter of bringing his children with him for the trip?" said Rizal.

Najib is currently in China on a six-day trade trip. He will return on Nov 6.