BEIJING -- Ownership of about 78 percent of China's collectively-owned rural land had been clarified by the end of June in a government campaign to protect farmers' land rights, the country's land watchdog said Sunday.

Local authorities should step up their efforts to certify ownership of all collectively-owned land in the countryside by the end of 2012 as planned, the Ministry of Land and Resources said in a statement on its website.

Vice-Minister Hu Cunzhi warned that authorities should not approve the expropriation or transfer of collectively-owned rural land that remains unidentified as of the end of this year.

The lack of legal proof of who owns rural land has left farmers' interests poorly protected. Land in China's countryside is either state owned or collectively owned.

The government proposed a plan in 2010 to identify and register the ownership of all collectively-owned rural land by the end of 2012, in a bid to better protect the interests of its 680 million farmers.