WRAPUP 5-China lets yuan break key 7 level for first time in decade as trade war worsens

(Adds onshore yuan domestic closing price, milestone, charts and analyst comments)

* Onshore yuan weakens to lowest level since financial crisis

* Offshore yuan hits lowest level on record

* PBOC ties drop to trade, says China's FX policy remains unchanged

* Shanghai Composite has weakest close since Feb. 22

By Andrew Galbraith and Winni Zhou

SHANGHAI, Aug 5 (Reuters) - China let the yuan breach the key 7-per-dollar level on Monday for the first time in more than a decade, in a sign Beijing might be willing to tolerate more currency weakness that could further inflame a trade conflict with the United States.

The sharp 1.4% drop in the yuan comes days after U.S. President Donald Trump stunned financial markets by vowing to impose 10% tariffs on the remaining $300 billion of Chinese imports from Sept. 1, abruptly breaking a brief ceasefire in a bruising trade war that has disrupted global supply chains and slowed growth.

Some analysts said the yuan move could unleash a dangerous new front in the trade hostilities - a currency war.

The People's Bank of China (PBOC) provided the early impetus for yuan bears by setting a daily rate for the currency at its weakest level in eight months.

Capital Economics Senior China Economist Julian Evans-Pritchard said the PBOC had probably been holding back against allowing a weaker yuan to avoid derailing trade negotiations with the United States.

"The fact that they have now stopped defending 7.00 against the dollar suggests that they have all but abandoned hopes for a trade deal with the U.S.," he said.

The PBOC gave few clues about its intentions.

In a statement on Monday, the central bank linked the yuan's weakness to the fallout from the trade war, but said it would not change its currency policy and that two-way fluctuations in the yuan's value are normal.

"Under the influence of factors including unilateralism, protectionist trade measures, and expectations of tariffs against China, the yuan has depreciated against the dollar today, breaking through 7 yuan per dollar," the PBOC said.

The central bank set the yuan's daily midpoint at 6.9225 per dollar before the market open, its weakest level since Dec. 3, 2018.

"Today's fixing was the last line in the sand," said Ken Cheung, senior Asian FX strategist at Mizuho Bank in Hong Kong.

"The PBOC has fully given the green light to yuan depreciation."

The onshore yuan finished the domestic session at 7.0352 per dollar, its weakest level since March 2008. Monday marked the first time the yuan had breached the 7-per-dollar level since May 9, 2008.