UPDATE 2-Engineers union urges rejection of Boeing contract offer

* SPEEA recommends members reject Boeing offer

* Boeing agrees to extend some terms of expired contract for four years

* Health care plans would remain with no rise in employee contribution

* Pension basic benefit would rise in company offer

Jan 17 (Reuters) - The union representing 23,000 Boeing Co engineers and technical workers urged members to reject the company's latest contract offer, which included an extension of previous terms aside from new proposals both parties had accepted during talks.

Boeing said its "best and final" proposal to the Society of Professional Engineering Employees in Aerospace (SPEEA) would roll forward the contract for four years.

"Agreeing to this contract as soon as possible will allow all of us to focus our time and energy on the immediate challenges facing the company," Boeing said in a statement.

Under the offer, existing employees "would see salary pools of 5 percent annually for the duration of the contract", Boeing said.

The company's health care plans would remain in place with no increase in employee contributions, and the pension basic benefit would be increased, Boeing added.

In response, the engineers union said that although the Boeing offer contained improvements, "both the Professional and Technical Negotiation Teams unanimously recommend rejection."

"While the company agreed to extend parts of the existing contracts, the offers put retirement benefits for all 23,000 engineers and technical workers, including retiree medical, at risk. In addition, Boeing's corporate negotiator said the company will end the pension for future employees," SPEEA said in a statement.

An escalating series of mishaps on Boeing's new 787 Dreamliner has strengthened the negotiating position for engineers, who are considered by aviation experts to be crucial to a safety review of the aircraft.

A team of experts from U.S. aviation authorities and Boeing arrived in Takamatsu in western Japan on Friday to inspect a 787 jet that was forced to make an emergency landing on Wednesday.

SPEEA had made its own "best and final" contract offer to Boeing on Wednesday, proposing to extend the contract for four more years and avert a strike to allow the aerospace company to focus on addressing safety concerns customers have with the new 787 Dreamliner.

The negotiations with SPEEA have been going on since April 2012. The previous contract expired in October.