A top American Senator today asked US President Barack Obama to press his Chinese counterpart, Hu Jintao on issues related to cyber security and rare earth elements.

"Cyber security and REEs greatly affect both the national and economic security of the United States, and I continue to be concerned about China's policies regarding these two strategic interests," New York Senator Kirsten Gillibrand said in a letter to Obama.

"I trust that these issues will be part of the agenda of your bilateral meeting among the other pressing issues such as the nuclear programs and proliferation activities of North Korea and Iran, Taiwan's security, and a myriad of trade and financial issues," she said in her letter.

Strong evidence suggests China was responsible for a number of cyber attacks against the US Department of Defence and other federal agencies, defense-related think tanks and contractors, and other private US companies, including Google, it said.

China also accounts for more than 95 per cent of the world?s REE production, materials that are critical to our high-tech, clean energy and defense industries that help fuel US economy, but China uses that stronghold to restrict export shipments to the US, costing the US jobs and hurting American economic development in emerging industries, she said.

"I applaud the approach of your administration toward constructive engagement of China on issues of vital importance to our country's security and economic development.

I believe that this State Visit provides an excellent opportunity to continue to strengthen the US-China relationship based on mutual interests and shared priorities, while also making clear that the relationship must be based on fairness, accountability, and security," Gillibrand said in her letter.