Money often comes from drug smuggling or fraud
The National Criminal Intelligence Service (NCIS) received 18,408 disclosures from the financial sector to its Economic Crime Unit (ECU).
Investigators believe the increase of nearly 27% from the previous year is as a result of better awareness of the problem and improvements to databases.
The law allows professionals to report suspicions of money laundering to the authorities.
Making a disclosure is not treated as a breach of any duty of confidentiality to a client.
High-profile cases
ECU head Andy Blezzard said the increase in disclosures this year was partly down to efforts to raise awareness by the authorities and trade bodies.
Awareness was also raised by the reporting of several large money laundering cases in the media.
He said the implementation of a new disclosures database had proved to be highly successful.
"On the down side, we note, once again, that whilst the majority of disclosures still originate from the banking sector, there are still many such organisations that disclose very few, if any, suspicious transaction reports."
He said that out of 575 registered banks only 170, less than 30%, made any suspicious transaction reports during last year.
'Vulnerable' institutions
He added: "Solicitors and accountants continue to give concern with very few reports being made despite their relative attractiveness to launderers.
"Accordingly, concerns remain that some of the financial institutions and sectors lack sufficient adherence to the regulations and disclosure obligations.
"They may not have adequate training provisions and reporting systems in place, leaving themselves vulnerable to laundering attempts."
He said ECU would tackle reticent sectors such as betting and gaming organisations, money transmission agents and bureaux de change.
Greater automation
"We are also mindful of the impact of technology," he said.
"Face-to-face contact with customers has reduced for banks and other financial institutions as more people have moved to telephone and postal banking.
"This is likely to continue with the spread of the internet, the establishment of call-centres and greater automation.
"The identification of suspicious transactions is therefore an increasing challenge for banks and other institutions."