John-Paul Conley got in to difficulties while swimming in the Don Khon 4,000 Islands region on Tuesday.
The 35-year-old, who was on a 12-month trip round-the-world with his partner Kate Downey, had been swimming in the river in southern Laos when he went missing.
After the news broke, well-wishers set up an online appeal to help pay for a local helicopter to carry out sweeps of the area.
MPs yesterday heard the appeal had raised more than £23,000. But last night donations on the Go Fund Me site had neared the £30,000 mark.
Patrick Ruddy, who set up the fund, wrote on the site: “I can’t stress enough the very real difference all of you are making in so many ways to the search for our friend John-Paul.
“A search that is going on right now, with resources you are directly providing.”
Speaking in the Commons Labour MP Tom Blenkinsop, who represents Middlesbrough South and East Cleveland, called on the Foreign Office to provide an update on the support being offered by the Government.
In a question to Commons Leader Andrew Lansley, he said: “John-Paul Conley, from Middlesbrough, has been missing since Tuesday, November 19, when he got caught in a current and was carried away while swimming in Don Khon, 4,000 islands region in Laos. Since yesterday, over £23,000 has been raised to aid the rescue effort.
“Can we have a statement at the earliest opportunity from the Foreign and Commonwealth Office into the search and rescue attempt for John-Paul?”
In reply, Mr Lansley said he would speak to Foreign Office Minister Hugo Swire, whose brief includes South-East Asia.
Mr Lansley said: “I know the House is concerned as you are concerned for your constituents. I will, if I may, talk to [Mr Swire] at the Foreign and Commonwealth Office and ask that he respond to you and the House as to what steps are able to be taken in this regard.”
Speaking to the BBC, Miss Downey said “time was crucial” in the search to find her partner.
“If anyone can get themselves out of this, it would be John,” she said.
“He’s a strong guy, he’s a very good swimmer and he’s got good practical skills.”
Miss Downey said she had been overwhelmed by the support from family and friends.