Shares in iron ore explorer Sundance Resources have plunged after another delay in its drawn-out takeover process.

China's Hanlong Group has proposed a $1.4 billion takeover of Sundance, but is awaiting approval for its bid by Chinese regulators.

The National Development and Reform Commission (NDRC) in China yesterday extended its provisional approval for Hanlong's acquisition by six months to July 30.

Hanlong still needs to find a financial partner for its takeover to proceed, in order to fund the development of Sundance's Mbalam-Nabeba project in Cameroon.

Funding in the order of $5 billion is needed to develop the mine and associate port and rail infrastructure.

Sundance shares had been suspended from trade since January 30 as Hanlong sought the extension of its provisional approval from the NDRC.

After resuming trade this morning, the shares fell heavily, and were down 3.5 cents, or 10.29 per cent, to 30.5 cents at 7.45am.

Hanlong's offer is for 45 cents per Sundance share.

Sundance on Friday said the Hanlong offer remained its best option, despite further delays.

"The simple fact is that no superior offer has emerged and the market share price has not approached the Hanlong bid," the company said in a statement.