WASHINGTON — Citing strong sales, Wal-Mart Stores Inc. and Cifra S.A., Mexico’s largest retailer, have eliminated a clause that would have allowed either company to withdraw from their retail partnership south of the border within three years.

“This will strengthen our partnership and will create more expansion opportunities,” said Dan Shinkle, spokesman at the Bentonville, Ark., headquarters of Wal-Mart, which launched its joint venture with Cifra in 1991. The retailer also announced that its partnership will expand to include Cifra’s apparel store division called Suburbia and its restaurant division called VIPS.

Wal-Mart now jointly operates in Mexico seven Club Aurrera/Sam’s Clubs; four Bodega Aurrera stores, which are lower-price discounters; two Almacenese Aurrera general merchandise stores; one Superamas supermarket, and two Wal-Mart Supercenters.

Shinkle would not comment on how many additional stores are planned in Mexico nor on sales figures. Analysts, however, said that the Sam’s Club in Mexico City is generating more than $100 million in sales, outperforming any of its other units in the warehouse club division, and that the supercenters in Mexico City are raking in sales of more than $120 million on an annualized basis.