Gwen Stefani and Blake Shelton apply for marriage licence in Oklahoma

US music stars Gwen Stefani and Blake Shelton look set to tie the knot after applying for a marriage licence in Oklahoma.

No Doubt singer Stefani, 51, and country music star Shelton, 45, announced their engagement in October last year.

They have been together for more than five years after meeting while coaches on the US version of TV talent show The Voice.

They applied for a marriage licence this week, according to the Johnston County Court Clerk.

In the state of Oklahoma, the licence is valid for 10 days.

Showbiz website TMZ reported Stefani and Shelton plan to marry this weekend, with Sunday being Independence Day in the US.

The chart-topping musicians have released several songs together, including Nobody But You, which reached number 18 on the Billboard Hot 100 last year.

Stefani and former husband Gavin Rossdale, with whom she shares three sons, divorced in 2016.

Shelton was previously married to singer Miranda Lambert but they announced they were divorced after four years of marriage in July 2015.

In 2017, he was named sexiest man alive by People magazine.