A man who wrote a social media post critical of China's decades-old land reform policies was sentenced to a year in prison, reports said Tuesday, amid a tightening of civil liberties and free speech.

The man, surnamed Miao, ran the Twitter-like Weibo social media account for the traffic police of Zizhou county in northern Shaanxi province, the Global Times newspaper reported Thursday.

In June 2015 he wrote a post that criticised China's land reform policy of 1950, which abolished landowners' rights and saw the violent confiscation of property and its redistribution to peasants.

Since that law was enacted, "a vigorous land reform was carried out across China, a movement under which people were killed for money and property, leading to hatred and decay of traditional moral values," he wrote in the now-deleted post, according to the Global Times.

"The land reform was the start of the collapse of Chinese moral values!"

The post was quickly scrubbed and the traffic police posted an apology blaming the manager's irresponsible work attitude for the "inappropriate remarks, which deeply wounded the feelings of the mass of internet users".

Miao was sentenced to one year in prison with one year and six months' reprieve for dereliction of duty by the local court, it said.

China has seen a sprawling crackdown on dissent under President Xi Jinping, restricting citizens' speech online and jailing hundreds of lawyers who had taken on civil rights cases considered sensitive by the ruling party.

Communist authorities oversee a vast censorship system -- dubbed the Great Firewall -- that aggressively blocks sites or snuffs out internet content and commentary on topics considered sensitive, such as Beijing's human rights record and criticism of the government.

In November China passed a controversial cybersecurity bill that banned internet users from publishing a wide variety of information, including anything that damages "national honour", "disturbs economic or social order" or is aimed at "overthrowing the socialist system".