Houston-area Kroger employees told the company Friday they may go on strike in seven days if no contract agreement is reached.

The Cincinnati-based grocery chain and the two United Food and Commercial Workers union locals representing 12,700 Houston-area employees have been negotiating a new contract since the last one expired March 31.

For the past week, Houston negotiations have taken a back seat to talks in Dallas, where workers have threatened to strike since their extension expired Sunday. The Dallas union agreed to a cooling-off period earlier this week to allow further talks.

The Houston contract requires the union to give seven days' notice before it can strike, so the earliest one would start is Friday, said union spokeswoman Amber Sparks.

The two sides in the Houston talks, disagreeing on wage increases and the health care plan, are expecting to meet Monday in Dallas, Kroger spokesman Russell Richard said.

If Dallas workers decide to strike between now and then, Houston Kroger employees might picket stores here in solidarity.

Union members have authorized leaders to call a strike in Houston if necessary, and Friday's announcement put Kroger on notice, Sparks said.

"We're hoping not to strike," she said.

But they're preparing for it. Employees said they have received strike booklets and have been asked to sign paperwork committing themselves to a strike.

"We were on yellow alert, now we're on orange alert," said Curtis Martin, a member of the union bargaining team who works at a Kroger in Galveston.