Gordon Brown plans to ban 100% mortgages in an attempt to prevent a repeat of the reckless loans by banks and building societies blamed for the credit crunch problems.

He has written to City watchdogs at the Financial Services Authority asking them to launch an urgent investigation into how such loans can be permanently outlawed.

The economic crisis has led to most financial institutions withdrawing 100% home loans - but the Prime Minister wants to make sure that they do not return when the recession is over.

Mr Brown also aims to persuade banks to refuse to give loans to people unless they can show they are earning enough money to meet their monthly mortgage payments.

In the past, most building societies would limit loans to three times an individual's earnings. But in the past few years, some banks threw caution to the wind and allowed people to borrow five times their salary - in some cases more.

Northern Rock, the first big bank to collapse, was among those that were accused of irresponsibly offering mortgages of 100%, and occasionally up to 125%, of the value of a property.

Many buyers who obtained such sums were the first to default on their loans, contributing to Northern Rock's demise and a series of bailouts by the taxpayer.

Meanwhile, Mr Brown last night appeared to have won the race with French President Nicolas Sarkozy to be the first European leader to meet Barack Obama in the White House.

Diplomatic sources said that the Prime Minister will have talks with the US President in Washington on March 3. The sources said they believed the timing would make Mr Brown the first European leader to meet Mr Obama since his inauguration in January.

However, it will be scant consolation for Mr Brown, as his predecessor Tony Blair met President Obama at a National Prayer Breakfast in Washington earlier this month.

FIRST-TIME BUYERS AND AFFORDABILITY
Year Number of mortgages Average age Average advance £ Average income £ Loan-to-value % Income multiple
Source: Council of Mortgage Lenders (February 2009)
1974 197,500 26 6,400 2,916 84 2.18
1975 259,000 27 7,200 3,500 86 2.07
1976 315,500 27 8,000 4,000 88 1.99
1977 328,500 27 8,376 4,451 88 1.85
1978 no data no data no data no data no data no data
1979 320,200 26 11,250 6,000 86 1.86
1980 314,400 26 13,000 7,392 84 1.73
1981 342,100 27 14,542 7,747 88 1.82
1982 433,800 28 15,000 8,040 93 1.83
1983 477,600 28 16,000 8,316 94 1.92
1984 531,300 27 17,950 9,028 94 1.99
1985 557,800 27 19,112 9,806 95 2.00
1986 612,700 27 22,000 10,669 95 2.10
1987 523,700 27 23,000 11,300 95 2.12
1988 580,300 28 25,650 12,500 95 2.22
1989 455,200 29 29,000 13,780 95 2.22
1990 409,200 28 35,000 15,500 95 2.31
1991 336,200 27 36,480 16,000 95 2.32
1992 447,600 28 36,337 16,120 95 2.31
1993 519,500 29 36,000 15,997 94 2.33
1994 532,100 29 36,498 16,120 95 2.34
1995 420,300 28 38,000 16,680 95 2.37
1996 465,300 28 39,811 17,308 95 2.36
1997 501,500 29 41,800 18,080 95 2.37
1998 525,200 29 45,000 19,600 93 2.38
1999 592,400 30 49,000 21,141 90 2.41
2000 500,200 30 51,253 22,018 90 2.42
2001 568,200 30 56,950 23,700 90 2.48
2002 531,800 31 69,000 26,644 90 2.67
2003 369,600 31 76,412 27,137 89 2.83
2004 358,100 31 90,000 29,270 87 3.03
2005 372,300 29 98,940 32,035 90 3.07
2006 401,000 29 108,865 33,762 90 3.23
2007 357,800 29 116,820 35,029 90 3.36
2008 194,200 29 110,469 34,575 87 3.27