MILAN, July 16 (Reuters) - Italian retail chain Gruppo Coin (GCN.MI) expanded its children's clothes activities with the acquisition of 54 shops on Friday and said sales at its existing stores were on a positive trend this year.

The 54 outlets will add to an existing 35 children's stores and help Coin meet its target for 150 in 2011, including franchised outlets, its chief executive Stefano Beraldo said in a statement.

Coin will invest only 150,000 euros in developing the 54 shops, a source close to the situation said.

Coin declined to name the seller of the stores, nor the price paid, but a market source said the stores had been sold by Italian clothing chain Magnolia.

A Milan-based retail analyst said Coin would aim to triple sales at the 54 shops and make them profitable by 2011 and as it converts them to its OVS Kids brand and introduces its own merchandise in the shops this year.

On group sales, Beraldo said the trend in the first part of the year was satisfactory, with same-store sales showing a positive trend in line with Coin's expectations.

At 1400 GMT, Coin shares were up 1.12 percent at 5.865 euros. The STOXX Europe 600 retail index0. SXRP was down 1.18 percent.

(Writing by Nigel Tutt, editing by Will Waterman)