Mexico's state oil monopoly Pemex this month will begin increasing exports to China by 30,000 barrels a day, the head of Pemex said on Saturday.

The two-year agreement between Pemex and China's Sinopec was signed in January, Pemex Chief Executive Emilio Lozoya said at a press conference in Sanya, China.

"This represents a landmark in the history of Pemex, since it is the first long-term contract of its kind signed with a Chinese company," Lozoya said.

The level of exports to China could increase over time as part of the agreement, he added.

Pemex sends most of its oil to Mexico's largest trade partner, the United States.

The oil company in 2012 exported an average of 1.256 million barrels a day, of which 85,000 barrels a day went to Asia.

Lozoya was at a press conference with Mexico's President Enrique Pena Nieto, who is on an official visit in China.

Pena Nieto and Pemex signed two separate agreements with Xinxing Cathay International Group and China National Petroleum Company for academic and technological cooperation.

At the same event, China's government signed an agreement of understanding with Mexican steel company Altos Hornos de Mexico .

The agreement between Pemex and the Chinese companies comes as Pena Nieto prepares to launch a major overhaul of the Mexican energy sector this year, aimed at making Pemex more efficient.

The Mexican oil industry has been hampered by under-investment and legal prohibitions on private participation.