Chinese factory-gate inflation edged up to 8.1 percent in April, the fastest rate since late 2004, showing a sustained build-up in price pressures that could keep consumer inflation  high.

The reading on the producer price index rose from 8 percent in March as food, energy and raw material costs all rose at double-digit paces.

"Usually it takes about six months for producer price pressure to be transmitted to consumer prices. But now the time lag is getting shorter," said Tang Jianwei, an analyst at Bank of Communications in Shanghai.

Consumer price inflation in the world's fastest-growing major economy is already at its highest level in more than 11 years at an annual rate of 8.3 percent.

Deputy Prime Minister Wang Qishan on Friday labeled inflation the biggest economic problem in China and reaffirmed that the government would maintain to a tight monetary policy.