Boksic's record wage claim has Robson in fury.
Boro will apply for a work permit for the 30-year-old Croatian striker after agreeing a pounds 2.5 million move from Lazio on a three-year contract.
But Robson blasted reports that Boksic would be paid pounds 63,000 a week - pounds 11,000 more than Manchester United skipper Roy Keane.
'Why is it that every time we sign a top-class player, people have to find an edge to it?' he said. 'They have to find some reason for why he would want to come to Middlesbrough almost to justify it.
'The wages quoted are a total nonsense. I got to hear about this long before anyone else and that's why we acted quickly and decisively. Talk of pounds 63,000 a week is utter rubbish.
'It's always the same whenever I bring a top player with a great reputation into this football club. It's either because of the money or it's because they're in somebody's reserves and they're finished.
'That's exactly what happened with Christian Ziege. When I brought him in, people were saying he was a has-been and had been in AC Milan's reserves for two years rotting, and look how he turned out.'
Boksic returned home on Thursday to await the outcome of his work permit application. Although Boro may have to go to appeal before being successful, they are confident the permit will be granted.
Robson said: 'We can't put a time-scale on it, but I hope it all goes through okay. I've always admired Alen Boksic as a player. When he's at his best, he's one of the best six strikers in the world so, hopefully, he can prove me right on that.'
Robson paraded latest signings Noel Whelan, formerly of Coventry City, and Joseph-Desire Job at a press conference yesterday and said he was still in the market for a defender - Aston Villa's Ugo Ehiogu has been consistently linked with a move to Teesside - and a midfielder, but much of the talk was of German defender Ziege.
Robson declined to talk about the player's situation but it is understood that his pounds 5.5 million move to Liverpool is drawing closer all the time.
And while the former AC Milan star is one man he does not want to lose, he said there would be departures before the start of the season.
He said: 'I have to thin the squad down a bit, but I will let the players know who I decide I will let go elsewhere because they may not get a chance to play at this club.
'That will depend on contract situations and those offers I receive from other clubs. I'm sure clubs around the country will be looking at our squad now knowing that a few players will be available for transfer.'
Meanwhile, Whelan and Job will make their debuts, along with French international Christian Karembeu, in Robbie Mustoe's testimonial game against Borussia Dortmund tomorrow.
Newcastle striker Alan Shearer will have one chance to prove his fitness for the club's curtain-raiser at Manchester United after being ruled out of today's friendly against Feyenoord in Rotterdam.
The 29-year-old former England skipper was not in the 17-man party after struggling to shake off a bout of tendinitis in his knee.
Now Shearer, who has played barely 20 minutes since returning for pre-season training after Euro 2000, has only next weekend's match against Espanyol in Barcelona to be fit for the match at Old Trafford on August 20.
Shearer had a scan on the knee earlier this week and, although that revealed no further damage, the injury remains a problem despite his assurances that he will be ready.
He said: 'The scan has shown that the knee is no worse than when I was scanned by England during the European Championships.
'I'm not that short of match fitness because I didn't stop playing until June 20 with England.
'All I need to be ready for Manchester United is one full game or a game-and-a-half. Pre-season matches don't matter apart from getting players ready for the important stuff.'
There was no place either in the travelling party for midfielder Kieron Dyer, who has had sore shins, while pounds 4 million signing Christian Bassedas is sidelined for six weeks after breaking a bone in his foot on the recent pre-season trip to the United States.
Gerard Houllier demands that his team are mates - and believes that will be the key to turning his squad of superstars into winners.
The Liverpool chief has spent pounds 50 million and nearly 20 months of painstaking team building.
He said: 'I want camaraderie, players have to get on well, be friends.'
Houllier's squad is in Belfast to play Benfica at Windsor Park today before travelling to Norway next week.
Robbie Fowler is injured but Michael Owen will start along with Sander Westerveld, Sami Hyypia, Gary McAllister, Dietmar Hamann and Titi Camara.
Houllier says anything less than a top-three finish this season will be failure, adding: 'I don't know my best team yet, we have more than 20 fine players and we are stronger than last season. We needed the competition because last season we found ourselves short of strikers through injuries.'