Lin Yueqin, a researcher with the Chinese Academy of Social Sciences, said many local governments want to acquire more land for projects to boost the economy, long considered an indicator of their career performance.
Also some local officials want to fatten their own pockets by illegally transferring land for non-farming uses, said Lin.
At the meeting, Wen urged the recently established nine land inspection bureaus nationwide to strengthen supervision on land acquisition.
China's arable land has reduced from 130 million hectares in 1996 to 122 million last year and nearly 40 million farmers have lost their farmland; and per capita arable land was 0.093 hectares, a third of the global average.
Wen called for a steady growth of the economy in the second half of the year.
He said that more attention should be paid to the structure of the economy and the pattern of economic growth; and that the nation would focus more on energy saving and environmental protection to promote sustainable development.
He demanded more efforts be made in such areas as raising farmers' incomes, curbing overheated investment in fixed assets, and boosting consumption.
Wen also said that in the next five years, China would create 45 million jobs, re-employ 45 million labourers in rural areas and keep the urban unemployment rate below 5 per cent.