SHANGHAI, July 4 (Reuters) - China's major state banks have lowered their dollar deposit rates for the second time in a month, seven banking sources with direct knowledge of the matter said, as authorities have stepped up efforts to arrest a slide in the yuan.

Interest rates offered by the "Big Five" state-owned lenders on most dollar deposits are now capped at 2.8%, down from 4.3% previously, said the people, who declined to be named as they were not authorised to speak to the media.

The People's Bank of China, which typically issues guidance on dollar deposit rates to state banks, declined to comment on the matter.

The lenders - Industrial and Commercial Bank of China , Bank of China , Agricultural Bank of China , China Construction Bank and Bank of Communications - did not immediately respond to requests for comment.

The new rates came into effect on July 1, said two of the sources, adding that some of the banks were not offering rates above the 2.8% cap for large deposits. Banks typically offer higher rates to deposits exceeding $1 million.

Lower rates would reduce the incentive for individuals to hold dollar deposits in China, which in turn could bolster the yuan and help to halt its slide in recent weeks to eight-month lows against the dollar. (Reporting by Winni Zhou, Samuel Shen and Jindong Zhang in Shanghai, Rong Ma in Beijing, and John Geddie in Tokyo; Editing by Edmund Klamann)