Retailer Sports Direct has increased its stake in UK football firm Umbro, which last week agreed a GBP285m (US$582m) takeover offer from Nike, to 29.9%.

The retail chain now has 43.7m ordinary shares in Umbro, up from a 15% stake previously.

The new shareholding is important since it sits just below the 30% threshold at which Sports Direct would have to launch a takeover offer.

Sports Direct's founder, Mike Ashley, is thought to have a close relationship with Nike, so analysts say it would not be in his interests to block its bid.

Umbro's board has unanimously recommended Nike's 193.06 pence per share offer, which together with a dividend values the company at approximately 195 pence per share. Sports Direct paid 194 pence per share when it bought its latest stake yesterday (30 October).

Another UK retailer, JJB Sports, bought a 10.12% stake in Umbro earlier in the month.

Nike intends to operate Umbro as a stand-alone affiliate brand, joining other units in the Nike portfolio, such as Converse, Cole Haan and Hurley International.