London-based HSBC has been accused by the US Senate of involvement in money laundering for drug trafficking and terrorism. The bank will attend a hearing before the lawmakers later on Tuesday. In a hard-hitting report, US lawmakers accused the global bank HSBC on Monday of opening the doors of the financial system to terrorists, drug dealers and money launderers. US senators found the London-based lender allowed affiliates in dangerous countries such as Mexico, Iran, Saudi Arabia, Bangladesh and Syria to move billions of dollars into the United States without adequate controls. \"The culture at HSBC was pervasively polluted for a long time,\" said Senator Carl Levin, chairman of the US Senate Permanent Subcommittee on Investigations, a congressional watchdog panel. \"In an age of international terrorism, drug violence in our streets ... and organized crime, stopping illicit money flows that support those atrocities is a national security imperative,\" he added. The report comes at a time when the banking sector is already taking heat for manipulating interest rates and for the risky sub-prime loans that led to the 2008 financial crisis. HSBC issued an apology and said it would improve its procedures. \"We will acknowledge that, in the past, we have sometimes failed to meet the standards that regulators and customers expect,\" HSBC said in a statement, adding: \"We will apologize, acknowledge these mistakes, answer for our actions and give our absolute commitment to fixing what went wrong.\" The bank is due to attend a Senate hearing later Tuesday.