In a tense encounter at the Mennaye Field, Munster 'A' produced the only tries of the fixture, courtesy of Danny Barnes and Ronan O'Mahony. The home side's nine points came off the boot of Aaron Penberthy, with the game finishing 10-9 in what proved to be a successful weekend for the Munstermen.
Leinster 'A' achieved their place in the last-four with a closely contested victory over English Championship side Bristol, ending 30-26.
Despite scores from Mariano Sambucetti and Ross Johnston, Bristol were unable to undo the half-time deficit and with Fionn Carr crossing the line for the Leinster 'A' team's fourt try, Girvan Dempsey's charges reached the semi-finals for the second successive year.
Newcastle and Bedford will represent England's second tier, following comprehensive victories by both home teams this weekend.
Newcastle enjoyed the greatest winning margin, holding off fellow promotion hopefuls Nottingham in a huge 72-17 victory at Kingston Park.
Three tries in the space of eight minutes from the Falcons set the tone for the clash on Friday night, followed by six more scores after the break against a young Nottingham outfit.
The victory sees Newcastle extend their winning streak to 27 matches - they are yet to lose a single game in either league or cup rugby this season.
Finally, Bedford Blues complete the semi-final line-up for the second time, having reached the 2011 British & Irish Cup final, only to lose out to Bristol.
The Blues beat Llanelli 32-18 at Goldington Road, with out-half Jake Sharp claiming 22 of the points, in addition to two tries from London Wasps-bound winger Josh Bassett.
Despite strong competition from the Welsh Principality side, Llanelli were unable to close the gap leaving the English Championship club on the road to a semi-final place.
2012/13 BRITISH & IRISH CUP SEMI-FINALS:
Matches to be played over the weekend of April 27/28 -
Bedford Blues v Newcastle Falcons
MUNSTER 'A' v LEINSTER 'A'
* The final will be played at the home ground of the winners of semi-final 1 (Bedford Blues v Newcastle Falcons)