Strachan returns to Parkhead to land triple signing for Middlesbrough

Robson has signed a two-and-a-half-year contract with the option of a further year after the two clubs agreed an undisclosed fee, while both Flood and Killen have joined the Teessiders on free transfers.

Flood's deal extends to June 2011 while Killen's runs until the end of the current season.

The three men, who all played for the Bhoys under Strachan, passed medicals on Teesside earlier this week.

The successful completion of the deals will come as a boost to Strachan, who will hope to be able to include his new recruits in the squad for Saturday's match with Sheffield United.

Boro currently lie in 11th place in the table, 14 points adrift of an automatic promotion place.

Their best chance of making a swift return to the top flight could be via the play-offs.

Midfielder Robson, 31, who won his seventh senior cap for Scotland in November, has a league title to his name and played Champions League football during his two years at Parkhead.

Republic of Ireland Under-21 international Flood, now 24, began his career at Manchester City and joined Celtic 12 months ago after two seasons on loan at Dundee United, while 28-year-old former Oldham striker Killen is a New Zealand international.

Their arrivals came as Boro confirmed that Egypt midfielder Mohamed Shawky has joined Turkish club Kayserispor on a free transfer.