San Juan, Oct 9 (IANS): The Puerto Rican government, citing an "unprecedented catastrophe", has asked the US for a significant new influx of money as the island sits on the brink of "a massive liquidity crisis", a media report said.

In a three-page letter sent to US congressional leaders on Sunday, Governor Ricardo Rossello requested more than $4 billion from various agencies and loan programme to "meet the immediate emergency needs of Puerto Rico", reports CNN.

"We are grateful for the federal emergency assistance that has been provided so far.

"However, absent extraordinary measures to address the halt in economic activity in Puerto Rico, the humanitarian crisis will deepen, and the unmet basic needs of the American citizens of Puerto Rico will become even greater," the letter read.

Us President Donald Trump's administration submitted a $29 billion disaster relief request to Congress last week to cover ongoing relief and recovery efforts in the wake of hurricanes Harvey, Maria and Irma, and to pay federal flood insurance claims.

The House is expected to vote on that measure as soon as this week.

But the administration has also been conducting its own review of Puerto Rico's precarious financial position, informed sources told CNN.

With the letter, Rossello, who congressional aides said has spent much of the last week phoning key lawmakers to urge action, made clear that at least in his view, the additional action needs to be taken immediately.

"Financial damages of this magnitude will subject Puerto Rico's central government, its instrumentalities, and municipal governments to unsustainable cash shortfalls," he wrote.

"As a result, in addition to the immediate humanitarian crisis, Puerto Rico is on the brink of a massive liquidity crisis that will intensify in the immediate future."

Rossello also pointed to a potential exodus of the island's inhabitants should aid not be available in a timely manner -- something he has also emphasised in conversations with lawmakers.

"This could lead to an acceleration of the high pace of outmigration of Puerto Rico residents to the US mainland impacting a large number of states as diverse as Florida, Pennsylvania, New Hampshire, Indiana, Wisconsin, Ohio, Texas, and beyond."