The two suitors didn't say how much they were offering for the 25 percent stake, which they previously had pursued separately. Those earlier offers were unsuccessful.
Kuwait-based Zain has been seeking a buyer for its Saudi division as part of a $12 billion deal for the parent company from Etisalat, a state-run telecom headquartered in Abu Dhabi that has expanded rapidly beyond its home market in the United Arab Emirates.
Zain owns a quarter of the Saudi division that bears its name. Another 45 percent is publicly traded, with the rest held by private shareholders.
Batelco CEO Peter Kaliaropoulos said he is confident a successful joint KHC-Batelco bid will create additional value for his company's shareholders. He described Batelco's role as a "technical partner" to KHC in pursuing the deal.
"We value (KHC's) leadership and we look forward to supporting them through an effective technical and business partnership," he said.
Bahrain's government, which is facing stiff and prolonged opposition from anti-goverenment protesters, owns more than half of Batelco. The company provides telecom services under its name in the island kingdom and Egypt, and owns stakes in five other telecom firms in the Mideast and India.
KHC's investments include stakes in a number of blue-chip Western companies, including Citigroup Inc. and News Corp.
A Zain spokesman said the company would comment only after its board had met and made a decision on the offer. He spoke on condition of anonymity in line with company policy.
The offer is good until Monday morning.
Etisalat launched its bid for Zain in September, but the takeover effort has dragged on longer than it expected.
Zain must dispose of its Saudi stake to satisfy regulators because Etisalat already has a stake in mobile operations in the kingdom.