At the price on offer from China Guangdong Nuclear Power Corp, Kalahari would be worth around 615 million pounds. CGNPC and Kalahari had been in talks on a 290 pence offer before Japan's Fukushima nuclear disaster in March.
A successful acquisition would boost commodity-hungry China's efforts to meet its growing energy needs.
Kalahari shares were down 3.2 percent at 224 pence by 1200 GMT on Thursday on news of the lower price tag and on the prospect a deal could be done at a lower price.
Kalahari said CGNPC reserved the right to make an offer below 243.55 pence with the agreement and recommendation of Kalahari's board.
Thursday's announcement of a new price came six months after previous talks at the higher price ended, an interval demanded by Britain's Takeover Panel rules although Kalahari had said on October 10 that talks had resumed. CGNPC now has until 1700 GMT on December 8 to make an offer or be forced to withdraw.
The new indicative bid price of 243.55 pence per share from the Chinese may be seen as slightly disappointing, Libertas analyst Roger Bade said.
It is too early to come to a conclusion as it is not clear whether China will bid for Extract at the same time.
Kalahari, whose key asset is a 42.74 percent interest in Extract Resources
Husab is potentially the second-largest uranium mine in the world. Exploration work is continuing on the project, currently the world's fourth-largest uranium-only deposit, with an updated resource estimate due next year.
Under Australian rules, CGNPC would be required to make a full takeover offer once it owns more than 20 percent of Extract, but the securities regulator can grant exceptions.
Extract said on Thursday the Australian Securities and Investments Commission has not ruled on whether CGNPC will have to make a takeover offer. The commission will likely not decide until a firm offer is on the table for Kalahari.
Based on the new proposed bid for Kalahari, Patersons Securities analyst Simon Tonkin said Extract was worth A$8.82 per share, or A$2.2 billion (1.3 billion pound), a 12 percent premium to its last trade. Extract shares were on a trading halt on Thursday ahead of Kalahari's announcement.
Last month, Kalahari said discussions had restarted with CGNPC after talks collapsed earlier this year.
In march, following the earthquake and nuclear disaster in Japan, the two companies agreed CGNPC could cut the price to 270 pence but failed to persuade British regulators to allow them to lower the value.
At the moment Rio do not appear to be taking part in discussions, said Bade. There is very little noise that Rio would get involved.
(Additional reporting by Clara Ferreira-Marques; Editing by Dan Lalor)