KPN is preparing to raise much needed cash from the sale of its stake in a US telecoms firm, following an earlier threat by Standard & Poor's, the international ratings agency, to downgrade the Dutch telecoms firm unless it reduced its debt by at least €5.4bn ($4.9bn).

Infonet Services, a US-based data communications services provider, said that KPN had formally requested that it register with the US Securities and Exchange Commission for the public sale of KPN's 54.4 million shares, an 18% stake.