Japan's Denso Corp. (6902.TO) and Aisan Industry Co. ( 7283.TO), two affiliates of Toyota Motor Corp. (7203.TO), Friday said they will deepen their ties in a bid to beef up their competitiveness in the area of fuel injection equipment.

The planned ties between Denso, Japan's largest automobile part maker by sales, and Aisan, a maker of electronic automobile components, come as demand for advanced fuel injectors from auto makers grows. Fuel injectors are key devices used in vehicles to regulate their fuel-efficiency.

Denso, which currently doesn't own a stake in Aisan, said in a press release it will launch a tender offer for the company, aiming to buy 5.5 million shares, or a 9.95% stake, at Y1,350 per share between May 14 and June 11. Toyota, Japan's largest auto maker by sales, holds a 23% stake in Denso and a 32.75% stake in Aisan.

Aisan said in a separate release that it agreed to the bid and will buy Denso shares worth up to Y1.5 billion by the end of this year through the market.

The purchase will lift Aisan's stake in its partner to 0.04% from the current 0.003%, a Denso spokesman said.

Toyota Industries Corp. (6201.TO), another Toyota Motor affiliate, also said Friday that it will offer 5.5 million Aisan shares to the bid. It owns a 17.3% stake in Aisan.

Denso needs to buy the shares through a tender offer bid as Japanese securities regulations prohibit a group from adding or purchasing shares without offering a tender offer bid if the group's holdings exceeds a third of a company.

After the bid, Denso and Toyota Motor will own more than a third of Aisan if Denso buys all the 5.5 million shares.

If offered, Denso will buy shares from other shareholders. In that case, Toyota Industries will offer only part of the 5.5 million shares it plans to offer, the Denso spokesman said.