SHANGHAI/HONG KONG, Nov 27 (Reuters) - China Vanke's

bonds tumbled at market open on Thursday, extending this week's

losses, after the state-backed developer sought to delay an

onshore bond repayment for the first time.

Several of Vanke's yuan bonds slumped more than 20%, with

some down around 40%, prompting the Shenzhen Stock Exchange to

suspend trading in six of the company's exchange-traded bonds as

of 0143 GMT.

Vanke's yuan bond due in March 2027 changed

hands at 50 per 100 par value in early trading, down nearly 30%.

The bond has dropped more than 40% this week.

Vanke said it is seeking bondholder approval to delay the

repayment of a 2 billion yuan ($282.6 million) onshore bond

due on December 15, a filing late on Wednesday

showed.

An onshore bond extension would be a first for the

state-backed property developer, surprising many market

participants and raising concerns over how willing Beijing is to

further support the crisis-hit sector.

Offshore, Vanke's dollar bond was bid at 30.4 cents on the

dollar, further down from around 40 cents on Wednesday, data

from Duration Finance showed. The bond was bid at around 55.4

cents on Tuesday.

The developer's bonds have been falling since financial

publication Octus reported on Tuesday that Beijing gave

preliminary guidance to the government of Shenzhen, where Vanke

is based, to consider a "market-oriented approach" for dealing

with the developer's debt, which is a euphemism for

restructuring, according to the report.

A debt restructuring by Vanke , with

364.3 billion yuan of interest-bearing liabilities, could also

potentially dwarf the impact of defaults by privately owned

peers Evergrande and Country Garden this decade.

Two people with knowledge of the situation told Reuters on

Wednesday that state-owned China International Capital

Corporation (CICC) had been brought in to assess Vanke's debt

and a debt restructuring was among the options the investment

bank featured in an internal report to the central government.

($1 = 7.0758 Chinese yuan renminbi)